CA1152802A - Electrophotographic member including a layer of amorphous silicon containing hydrogen - Google Patents
Electrophotographic member including a layer of amorphous silicon containing hydrogenInfo
- Publication number
- CA1152802A CA1152802A CA000382318A CA382318A CA1152802A CA 1152802 A CA1152802 A CA 1152802A CA 000382318 A CA000382318 A CA 000382318A CA 382318 A CA382318 A CA 382318A CA 1152802 A CA1152802 A CA 1152802A
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- CA
- Canada
- Prior art keywords
- layer
- approximately
- amorphous silicon
- hydrogen
- atomic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
- G03G5/02—Charge-receiving layers
- G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
- G03G5/08—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic
- G03G5/082—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic and not being incorporated in a bonding material, e.g. vacuum deposited
- G03G5/08214—Silicon-based
- G03G5/08235—Silicon-based comprising three or four silicon-based layers
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
- G03G5/14—Inert intermediate or cover layers for charge-receiving layers
- G03G5/142—Inert intermediate layers
- G03G5/144—Inert intermediate layers comprising inorganic material
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
- G03G5/14—Inert intermediate or cover layers for charge-receiving layers
- G03G5/147—Cover layers
- G03G5/14704—Cover layers comprising inorganic material
Abstract
Abstract:
An electrophotographic member has at least a supporting and a photoconductor layer formed mainly of amorphous silicon and is characterized in that the amor-phous silicon contains at least 50 atomic-% of silicon and at least 1 atomic-% of hydrogen as an average within the layer, and that a part which is at least 10 nm thick from a surface or/an interface of the photoconductor layer towards the interior of the photoconductor layer has a hydrogen content in a range of at least 1 atomic-% to at most 40 atomic-% and an optical forbidden band gap in a range of at least 1.3 eV to at most 2.5 eV. The amorphous silicon also has the property that the intensity of at least one of peaks having centers at wave numbers of approximately 2,200 cm-1, approximately 1,140 cm-1, approximately 1,040 cm-1, approximately 650 cm-1, approximately 860 cm-1 and approximately 800 cm-1 in an infrared absorption spectrum attributed to a bond between silicon and oxygen does not exceed 20% of that of a higher one of peaks having centers at wave numbers of approximately 2,000 cm-1 and approximately 2,100 cm-1 attributed to a bond between silicon and hydrogen. By this means the dark decay characteristics are improved and a satisfactory surface potential can be secured. In addition, the characteristics are very stable versus time.
An electrophotographic member has at least a supporting and a photoconductor layer formed mainly of amorphous silicon and is characterized in that the amor-phous silicon contains at least 50 atomic-% of silicon and at least 1 atomic-% of hydrogen as an average within the layer, and that a part which is at least 10 nm thick from a surface or/an interface of the photoconductor layer towards the interior of the photoconductor layer has a hydrogen content in a range of at least 1 atomic-% to at most 40 atomic-% and an optical forbidden band gap in a range of at least 1.3 eV to at most 2.5 eV. The amorphous silicon also has the property that the intensity of at least one of peaks having centers at wave numbers of approximately 2,200 cm-1, approximately 1,140 cm-1, approximately 1,040 cm-1, approximately 650 cm-1, approximately 860 cm-1 and approximately 800 cm-1 in an infrared absorption spectrum attributed to a bond between silicon and oxygen does not exceed 20% of that of a higher one of peaks having centers at wave numbers of approximately 2,000 cm-1 and approximately 2,100 cm-1 attributed to a bond between silicon and hydrogen. By this means the dark decay characteristics are improved and a satisfactory surface potential can be secured. In addition, the characteristics are very stable versus time.
Description
8~;~
Electrophoto~raphic member This invention relates to improvements in an electro-photographic member that employs amorphous silicon as the photoconductive material.
Photoconductive materials hitherto used for electro-photographic members include inorganic substances such as Se, CdS and ZnO and organic substances such as poly-N-vinyl carbazole (PVK) and trinitrofluorenone (TNF). They exhibit high photoconductivities. However~ when forming photocon-ductive layers using these materials as they are or by dispersing powders thereof~in binders of organic substances, there has been the disadvantage that the layers exhibit insufficient hardness, so that their sur~aces tend to be flawed or~to wear away during operation as electrophoto-graphic members. In addition, many of these materials are substances harmful to the~human body. It is therefore undesirable that such layers should wear away and perhaps adhere to copy paper, even in small amounts. To avoid these disadvantages, it has been proposed to employ amorphous silicon as a photoconductive layer (Japanese Laid-open Patent Application No. 54-78135). An amorphous silicon layer is higher in hardness than the above mentioned conventional photoconductive layers, and is 8~
Electrophoto~raphic member This invention relates to improvements in an electro-photographic member that employs amorphous silicon as the photoconductive material.
Photoconductive materials hitherto used for electro-photographic members include inorganic substances such as Se, CdS and ZnO and organic substances such as poly-N-vinyl carbazole (PVK) and trinitrofluorenone (TNF). They exhibit high photoconductivities. However~ when forming photocon-ductive layers using these materials as they are or by dispersing powders thereof~in binders of organic substances, there has been the disadvantage that the layers exhibit insufficient hardness, so that their sur~aces tend to be flawed or~to wear away during operation as electrophoto-graphic members. In addition, many of these materials are substances harmful to the~human body. It is therefore undesirable that such layers should wear away and perhaps adhere to copy paper, even in small amounts. To avoid these disadvantages, it has been proposed to employ amorphous silicon as a photoconductive layer (Japanese Laid-open Patent Application No. 54-78135). An amorphous silicon layer is higher in hardness than the above mentioned conventional photoconductive layers, and is 8~
- 2 -hardly toxic. However, an amorphous silicon layer exhibits a resistivity in the dark that is too low for an electrophotographic member. An amorphous silicon layer having a high resistivity of the order of 101 Q .cm exhibits a gain that is too low, and is unsatisfactory as an electrophotographic member. To overcome this disadvantage, there has been proposed a structure wherein at least two sorts of amorphous silicon layers having different conductivity types, such as the n-type, n+-type, p-type, p+-type and i-type, are formed into a junction and wherein photo-carriers are generated in a depletion layer formed at the junction. (Japanese Laid-open Patent Application No. 54-1217~3). However, when a depletion layer is thus formed by combining two or more layers of different conductivity types into a junction, it is difficult to form the depletion layer at the surface of the photoconductive layer. As a result, the important surface part of the photoconductive layer, which must hold a charge pattern, exhibits a low resistivity, giving rise to lateral flow of the charge pattern, with a consequent risk of degradation of resolution of the electrophotography.
This invention has for its object to provide an electrophotographic member employing amorphous silicon that has good dark decay characteristics and a high photosensitivity. The characteristics of the member are also very stable versus time.
In order to accomplish the object, the invention provides an electrophotographic member having at least a supporting and a photoconductcr layer which is principally formed of amorphous silicon; characterized in that said amorphous silicon contains at least 50 atomic-% of silicon and at least 1 atomic-~ of hydrogen as an average within said layer, and that a part which is at least 10 nm thick from a surface or/an interface of said photoconductor 8~
layer towards the interior of said photoconductor layer has a hydrogen content in a range of at least 1 atomic-%
to at most 40 atomic-% and an optical forbidden band gap in a range of at least 1.3 eV to at most 2.5 eV and also has the property that the intensity oE at least one of peaks having centers at wave numbers of approximately 2,200 cm 1, approximately 1,140 cm~l, approximately 1,040 cm~l, approximately 650 cm~l, approximately 860 cm 1 and approximately 800 cm 1 in an infrared lQ absorption spectrum attributed to a bond between silicon and oxygen does not exceed 20 % of that of a higher one of peaks having centers at wave numbers of approximately 2,000 cm 1 and approximately 2,100 cm 1 attributed to : a bond between silicon and hydrogen.
Examples of the invention are illustrated in the accompanying drawings, in which:
Figures 1 and 9 are graphs each showing the infrared absorption spectrum of amorphous silicon, Figure 2 is a schematic illustration for explaining reactive sputtering equipment,~
Figures 3 and 4 are graphs showing the relationships between the pressure of a gas during preparation of amorphous silicon and the intensities of peaks contributing to the bond between silicon and oxygen, Figure 5 is a graph showing the relationship between the sputtering atmosphere and the Vickers hardness of amorphous silicon, Figures 6 and 7 are views each showing the sectional structure of an electrophotographic member,
This invention has for its object to provide an electrophotographic member employing amorphous silicon that has good dark decay characteristics and a high photosensitivity. The characteristics of the member are also very stable versus time.
In order to accomplish the object, the invention provides an electrophotographic member having at least a supporting and a photoconductcr layer which is principally formed of amorphous silicon; characterized in that said amorphous silicon contains at least 50 atomic-% of silicon and at least 1 atomic-~ of hydrogen as an average within said layer, and that a part which is at least 10 nm thick from a surface or/an interface of said photoconductor 8~
layer towards the interior of said photoconductor layer has a hydrogen content in a range of at least 1 atomic-%
to at most 40 atomic-% and an optical forbidden band gap in a range of at least 1.3 eV to at most 2.5 eV and also has the property that the intensity oE at least one of peaks having centers at wave numbers of approximately 2,200 cm 1, approximately 1,140 cm~l, approximately 1,040 cm~l, approximately 650 cm~l, approximately 860 cm 1 and approximately 800 cm 1 in an infrared lQ absorption spectrum attributed to a bond between silicon and oxygen does not exceed 20 % of that of a higher one of peaks having centers at wave numbers of approximately 2,000 cm 1 and approximately 2,100 cm 1 attributed to : a bond between silicon and hydrogen.
Examples of the invention are illustrated in the accompanying drawings, in which:
Figures 1 and 9 are graphs each showing the infrared absorption spectrum of amorphous silicon, Figure 2 is a schematic illustration for explaining reactive sputtering equipment,~
Figures 3 and 4 are graphs showing the relationships between the pressure of a gas during preparation of amorphous silicon and the intensities of peaks contributing to the bond between silicon and oxygen, Figure 5 is a graph showing the relationship between the sputtering atmosphere and the Vickers hardness of amorphous silicon, Figures 6 and 7 are views each showing the sectional structure of an electrophotographic member,
3~ Figure 8 is a schematic view showing the construction of a laser beam printer, and Figure 10 is a graph showing the variations-with-time of the surface potentials of several amorphous silicon layers.
8~2 Detailed Description _f the Preferred Embodiments An amorphous silicon layer that is made only of pure silicon exhibits a high localized state densisty, and has almost no photoconductivity. However, such an amorphous silicon layer can have the localized states reduced sharply and be endowed with a high photoconductivity by doping it with hydrogen, or it can be turned into conductivity types such as the p-type or n-type by doping it with impurities. As elements effective to reduce the localized state density in the amorphous silicon as described above, there are the halogen group such as fluorine, chlorine, bromine and iodine, in addition to hydrogen. Although the halogen group has the effect of reducing the localized state density in the amorphous silicon, it cannot greatly vary the optical forbidden band ~ap of the amorphous silicon. In contrast, hydrogen doping can sharply increase the optical forbidden band gap of the amorphous silicon or can increase the resistivity thereof. It is thus especiall-y useful for obtaining a high-resistivity photoconductive layer.
In a light receiving device employing the storage mode~ such as an electrophotographic member, the resistivity of the photoconductive layer must satisfy the following two requirements:
(1) The resistivity of the photoconductive layer must be above approximately 101 Q .cm, lest charges stuck on the surface of the layer by corona discharge or the like should be discharged in the thickness direction of the layer before exposure.
~2) The sheet resistance of the photoconductive layer must also be sufficiently high, lest a charge pattern formed on the surface of the photoconductive layer upon exposure should disappear before developing due to lateral flow of the charges. In terms of resistivity, this ~ .
8~
requires it to be above approximately 101 Q .cm as in the preceding item.
In order to meet these requirements the resistivity of and near the surface of the photoconductive layer must be above approximately 101 Q .cm, but this resistivity need not be possessed uniformly in the thickness direction of the layer. Letting denote the time constant of the dark decay in the thickness dlrection of the layer, C
denote the capacitance per unit area of the layer and R
denote the resistance in the thickness direction per unit area of the layer, the following relation holds:
T = R C
The time constant ~ may be sufficiently long compared with the time from electrification to developing, and the resistance R may be sufficiently great in the thickness direction of the layer viewed macroscopically.
The present inventors have discovered that, as a factor that determines the macroscopic resistance in the thickness direction of the layer in a high-resistivity 2Q thin-film device, such as an electrophotographic member, charges in]ected from an interface with an electrode play an important role, besides the resistivity of the layer itself.
To block the injection of charges from a substrate side supporting the photoconductive layer, a method can be used in which a junction such as p-n junction is formed in the amorphous silicon layer near the substrate and is reverse-biased by an external electric field. This method, however, involves difficulty in meeting requirement (2) described above.
In the preferred form of the invention, the surface and the substrate side interface of the amorphous silicon are constructed as indicated above and the resistivity of the layer is made at least 101 Q .cm.
8~;~
Ordinarily, such a high-resistivity region is an intrinsic semiconductor (i-type). Such a region functions as a layer that blocks the injection of charges from the electrode into the photoconductive layer, and can simultaneously be effectively used as a layer that stores the surface charges. The thickness of the high-resistivity amorphous silicon layer needs to be at least 10 nm, lest the charges should pass through the region due to the tunnel effect. Further, in order to effectively block the injection of charges from the electrode, it is also effective to interpose a charge injection blocking layer of Si02, Ce02, Sb2S3, Sb2Se3, As2S3, As2Se3 or the like with a thickness of approximately 10 - 100 nm between the electrode and the amorphous silicon layer.
The localized state density in the pure amorphous silicon containing no hydroqen is presumed to be of the order of 102 /cm3. Supposing that hydrogen atoms extinguish the localized states at 1 : 1 when doping such amorphous silicon with hydrogen, all the localized states ought to be extinguished with a hydrogen-doping quantity of approximateIy 0~1 atomic-%. Actual study, however, has revealed that when the hydrogen content exceeds approximately 1 atomic-%l an amorphous silicon film is obtained that has a photoconductivity sufficient for electrophotography.
The present inventors have discovered that, if the hydrogen content of the amorphous silicon layer is too high, the characteristics of the layer are unfavorable.
At a content of several atomic-%, hydrGgen contained in amorphous silicon functions merely to extinguish the localized states within the amorphous silicon. However, when the content becomes excessive, the structure of the amorphous silicon itself changes and becomes the so-called polymeric structure such as (-SiH2-). In this regard, amorphous silicon up to approximately 65 atomic-~ in terms of the hydrogen content has been produced. With such amorphous silicon with a polymer structure, however, the travelling property of carriers generated by the photo excitation has been found to be inferior, with the result that satisfactory photoconductivity has become unattain-able. As a result of this study, the hydrogen content actually suitable for use in electrophotography has been found to be at least 1 atomic-% and at most 40 atomic-%.
; The hydrogen must bond with the silicon atoms for effectively extinguishing the localized states within the amorphous silicon. A good expedient for judging this point is a method in which the optical forbidden band gap is investigated. If the hydrogen is contained in the amorphous silicon in a form yielding an effective bond, the optical forbiddgen band gap increases with the hydrogen content. It has been verified that the optical forbidden band gap corresponding to the hydrogen content suitable for electrophotography (from l atomic-% to 40 atomic-%) falls in a range of from~1.3 eV to 2.5 eV.
Further, in order to retain the photoconductivity and high resistivity value of the amorphous silicon layer for a long time, the infrared absorption characteristics stated before need to be achieved. Shown by a solid line A in Figure l is the infrared absorption curve of amorphous silicon of good quality. Absorption peaks (indicated by arrows~ are noted at wave numbers of approximately 2,100 cm~l, 2,000 cm~l, 890 cm~l, 850 cm l and 640 cm l. All these peaks are attributed to the bond between silicon and hydrogen, it being understood that hydrogen efficiently bonds with silicon to extinguish the localized states within the layer. Under certain conditions of production, however, even an amorphous silicon layer that initially exhibits apparently good characteristics has these varied with time. Such a layer is unfavorable for use in electrophotography where it will undergo such severe usage as exposure to corona discharge, and can especially incur a conspicuous degradation in dark decay characteristics.
The inventors' study has revealed that this drawback is chiefly caused by an insufficient denseness of the skeleton structure of the amorphous silicon itself.
Expedients ef~ective for find out that such layer is liable to vary in quality have been known. One of them is to measure the aforecited infrared absorption curve, and the other is to measure the hardness of the amorphous ~ silicon layer.
~It has been discovered that when an infrared absorption measurement is made on an amorphous silicon layer whose characteristics degrade, several peak:s are observed from the beginning besides those attributed to the bond between silicon and hydrogen. These additional 2Q peaks are indicated by the broken line B in Figure 1 and may become conspicuous due to variations and increases with time. These peaks have centers at wave numbers of approximately 2,200 cm~1, approximately 1,140 cm 1, approximately 1,040 cm 1, approximately 650 cm 1, approximately 860 cm 1 and approximately 800 cm 1, and all are attributed to the bond between silicon and oxygen. They are somewhat different in size, the peak having a center at 1,140 cm 1 being the most conspicuous.
As illustrated in Figure 1, when the infrared absorption characteristics of the amorphous silicon layer are measured, the absorption peaks attributed to the bond between silicon and hydrogen are observed. Among them, the peaks at the wave numbers of approximately 2,100 cm~l and 2,000 cm~1 are attributed to the stretching 8~2 g vibration. It has been determined that, if the intensity of the greatest one of the peaks based on the bond between silicon and oxygen is no more than 20% of that of the greater one of the peaks based on the stretching vibration, such amorphous silicon will stably hold a high photoconductivity. This method is very effective in the production of electrophotographic members because it can simply detect amorphous silicon layers of inferior quality.
Regarding oxygen, it has been reported that, when oxygen is contained in a layer as a result of being added by a reaction gas during the preparation of the amorphous silicon, it contributes to an enhancement of the photoconductivity of the layer (published in, for example, Phys, Rev. Lett., 41, 1492(1978)). However, in this case the oxygen enters from the beginning in a form in which it effectively extinguishes the localized states in the amorphous silicon. Unlike the peaks described above, therefore, the maximum infrared absorption peak value exists in the vicinity of approximately 930 cm l.
Accordingly, such oxygen intentionally added in advance differs from the extrinsic oxygen forming the cause of the characteristics degradation as stated in this invention, and it forms no hindrance to the method of assessment of the amorphous silicon layer of this invention relying on the comparison of peak values.
Although the causes of the peaks are not yet entirely clear, it is presumed that the peak lying principally at 930 cm 1 in the case of intentionally adding oxygen will be a bond in the form of (-Si-0-), while the peaks changing with the lapse of time (at 1,140, 1,040, 650, 860 and 800 cm 1) will be attributed to the bond of sia~.
Known well as methods for forming amorphous silicon containing hydrogen (usually, denoted by a-Si:H) a~e (1) the glow discharge process based on the low-temperature decomposition of monosilane SiH4, (2) the reactive sputtering process in which silicon is sputter-evaporated in an atmosphere containing hydrogen, (3) the ion-plating process, etc.
When forming the layer by any of the various layer-forming methods, the hydrogen content of the amorphous silicon layer can be varied by controlling the substrate temperature, the concentration of hydrogen in the atmosphere or the input power, etc.
With any of the processes, a layer having the best photoelectric conversion characteristics is obtained when the substrate temperature during the formation of the layer is 150 - 250 C. In the case of the glow discharge process, a layer of good photoelectric conversion 15 characteristics has a~s low a resistivity as 106 _ 107 Q .cm and is unsuitable for electrophotography.
Therefore, such a consideration as doping the layer with a slight amount of boron to raise its resistivity is necessary. In contrast, the reactive sputtering process 20 can produce a layer having a resistivity of at least 10l Q .cm, besides good photoelectric conversion characteristics. Moreover~ it ean ~orm a uniform layer of large area by employing a sufficiently large sputtering target. It ean therefore be said to be particularly 25 useful for forming a photoconductive layer for eleetrophotography.
Reaetive sputtering is usually performed by equipment such as shown in Figure 2, wherein numeral 31 designates a bell jar, numeral 32 an evacuating system, numeral 33 a 30 radio-frequency power source, numeral 34 a sputtering target, numeral 35 a substrate holder, and numeral 36 a substrate. Sputtering equipment includes, not only structure designed to perform a sputter-evaporation on a flat substrate as illustrated, but also structure that can 8~2 perform a sputter-evaporation on a cylindrical or drum-shaped substrate, and such alternatives can be employed as required.
Reactive sputtering is carried out by evacuating the bell jar 31, introducing hydrogen and an inert gas such as argon thereinto, and supplying a radio-frequency voltage from the source 33 to cause a discharge,. The quantity of hydrogen contained in a layer so formed is determined principally by the pressure of hydrogen in the atomosphere during discharge. An amorphous silicon layer containing hydrogen in a manner suited to this invention is produced when the hydrogen pressure during sputtering lies in a range of from 5 x 10 5 Torr to ~ x 10 3 Torr.
Further, when the pressure of the gas is kept below 1 x 10 2 Torr, an'amorphous silicon layer of good stability is obtained.
The lower limit of pressure of the gas is determined by maintenance of the discharge, and is approximately 1 x 10 4 Torr when employing magnetron sputtering. For the deposition rate of the layer at this time, a value of 1 A/sec. - 30 A/sec. is preferableO
When preparing an amorphous silicon layer by a reactive,sputtering process, it has been found that a layer liable to change in quality is formed if the pressure o~ the gas during the reaction exceeds a certain value. Figures 3 and 4 show the circumstances, note being , especially taken of the peaks of 1,14~ cm 1 and 1,040 cm lo Figure 3 illustrates samples produced by the conventional reactive sputtering process, while Figure
8~2 Detailed Description _f the Preferred Embodiments An amorphous silicon layer that is made only of pure silicon exhibits a high localized state densisty, and has almost no photoconductivity. However, such an amorphous silicon layer can have the localized states reduced sharply and be endowed with a high photoconductivity by doping it with hydrogen, or it can be turned into conductivity types such as the p-type or n-type by doping it with impurities. As elements effective to reduce the localized state density in the amorphous silicon as described above, there are the halogen group such as fluorine, chlorine, bromine and iodine, in addition to hydrogen. Although the halogen group has the effect of reducing the localized state density in the amorphous silicon, it cannot greatly vary the optical forbidden band ~ap of the amorphous silicon. In contrast, hydrogen doping can sharply increase the optical forbidden band gap of the amorphous silicon or can increase the resistivity thereof. It is thus especiall-y useful for obtaining a high-resistivity photoconductive layer.
In a light receiving device employing the storage mode~ such as an electrophotographic member, the resistivity of the photoconductive layer must satisfy the following two requirements:
(1) The resistivity of the photoconductive layer must be above approximately 101 Q .cm, lest charges stuck on the surface of the layer by corona discharge or the like should be discharged in the thickness direction of the layer before exposure.
~2) The sheet resistance of the photoconductive layer must also be sufficiently high, lest a charge pattern formed on the surface of the photoconductive layer upon exposure should disappear before developing due to lateral flow of the charges. In terms of resistivity, this ~ .
8~
requires it to be above approximately 101 Q .cm as in the preceding item.
In order to meet these requirements the resistivity of and near the surface of the photoconductive layer must be above approximately 101 Q .cm, but this resistivity need not be possessed uniformly in the thickness direction of the layer. Letting denote the time constant of the dark decay in the thickness dlrection of the layer, C
denote the capacitance per unit area of the layer and R
denote the resistance in the thickness direction per unit area of the layer, the following relation holds:
T = R C
The time constant ~ may be sufficiently long compared with the time from electrification to developing, and the resistance R may be sufficiently great in the thickness direction of the layer viewed macroscopically.
The present inventors have discovered that, as a factor that determines the macroscopic resistance in the thickness direction of the layer in a high-resistivity 2Q thin-film device, such as an electrophotographic member, charges in]ected from an interface with an electrode play an important role, besides the resistivity of the layer itself.
To block the injection of charges from a substrate side supporting the photoconductive layer, a method can be used in which a junction such as p-n junction is formed in the amorphous silicon layer near the substrate and is reverse-biased by an external electric field. This method, however, involves difficulty in meeting requirement (2) described above.
In the preferred form of the invention, the surface and the substrate side interface of the amorphous silicon are constructed as indicated above and the resistivity of the layer is made at least 101 Q .cm.
8~;~
Ordinarily, such a high-resistivity region is an intrinsic semiconductor (i-type). Such a region functions as a layer that blocks the injection of charges from the electrode into the photoconductive layer, and can simultaneously be effectively used as a layer that stores the surface charges. The thickness of the high-resistivity amorphous silicon layer needs to be at least 10 nm, lest the charges should pass through the region due to the tunnel effect. Further, in order to effectively block the injection of charges from the electrode, it is also effective to interpose a charge injection blocking layer of Si02, Ce02, Sb2S3, Sb2Se3, As2S3, As2Se3 or the like with a thickness of approximately 10 - 100 nm between the electrode and the amorphous silicon layer.
The localized state density in the pure amorphous silicon containing no hydroqen is presumed to be of the order of 102 /cm3. Supposing that hydrogen atoms extinguish the localized states at 1 : 1 when doping such amorphous silicon with hydrogen, all the localized states ought to be extinguished with a hydrogen-doping quantity of approximateIy 0~1 atomic-%. Actual study, however, has revealed that when the hydrogen content exceeds approximately 1 atomic-%l an amorphous silicon film is obtained that has a photoconductivity sufficient for electrophotography.
The present inventors have discovered that, if the hydrogen content of the amorphous silicon layer is too high, the characteristics of the layer are unfavorable.
At a content of several atomic-%, hydrGgen contained in amorphous silicon functions merely to extinguish the localized states within the amorphous silicon. However, when the content becomes excessive, the structure of the amorphous silicon itself changes and becomes the so-called polymeric structure such as (-SiH2-). In this regard, amorphous silicon up to approximately 65 atomic-~ in terms of the hydrogen content has been produced. With such amorphous silicon with a polymer structure, however, the travelling property of carriers generated by the photo excitation has been found to be inferior, with the result that satisfactory photoconductivity has become unattain-able. As a result of this study, the hydrogen content actually suitable for use in electrophotography has been found to be at least 1 atomic-% and at most 40 atomic-%.
; The hydrogen must bond with the silicon atoms for effectively extinguishing the localized states within the amorphous silicon. A good expedient for judging this point is a method in which the optical forbidden band gap is investigated. If the hydrogen is contained in the amorphous silicon in a form yielding an effective bond, the optical forbiddgen band gap increases with the hydrogen content. It has been verified that the optical forbidden band gap corresponding to the hydrogen content suitable for electrophotography (from l atomic-% to 40 atomic-%) falls in a range of from~1.3 eV to 2.5 eV.
Further, in order to retain the photoconductivity and high resistivity value of the amorphous silicon layer for a long time, the infrared absorption characteristics stated before need to be achieved. Shown by a solid line A in Figure l is the infrared absorption curve of amorphous silicon of good quality. Absorption peaks (indicated by arrows~ are noted at wave numbers of approximately 2,100 cm~l, 2,000 cm~l, 890 cm~l, 850 cm l and 640 cm l. All these peaks are attributed to the bond between silicon and hydrogen, it being understood that hydrogen efficiently bonds with silicon to extinguish the localized states within the layer. Under certain conditions of production, however, even an amorphous silicon layer that initially exhibits apparently good characteristics has these varied with time. Such a layer is unfavorable for use in electrophotography where it will undergo such severe usage as exposure to corona discharge, and can especially incur a conspicuous degradation in dark decay characteristics.
The inventors' study has revealed that this drawback is chiefly caused by an insufficient denseness of the skeleton structure of the amorphous silicon itself.
Expedients ef~ective for find out that such layer is liable to vary in quality have been known. One of them is to measure the aforecited infrared absorption curve, and the other is to measure the hardness of the amorphous ~ silicon layer.
~It has been discovered that when an infrared absorption measurement is made on an amorphous silicon layer whose characteristics degrade, several peak:s are observed from the beginning besides those attributed to the bond between silicon and hydrogen. These additional 2Q peaks are indicated by the broken line B in Figure 1 and may become conspicuous due to variations and increases with time. These peaks have centers at wave numbers of approximately 2,200 cm~1, approximately 1,140 cm 1, approximately 1,040 cm 1, approximately 650 cm 1, approximately 860 cm 1 and approximately 800 cm 1, and all are attributed to the bond between silicon and oxygen. They are somewhat different in size, the peak having a center at 1,140 cm 1 being the most conspicuous.
As illustrated in Figure 1, when the infrared absorption characteristics of the amorphous silicon layer are measured, the absorption peaks attributed to the bond between silicon and hydrogen are observed. Among them, the peaks at the wave numbers of approximately 2,100 cm~l and 2,000 cm~1 are attributed to the stretching 8~2 g vibration. It has been determined that, if the intensity of the greatest one of the peaks based on the bond between silicon and oxygen is no more than 20% of that of the greater one of the peaks based on the stretching vibration, such amorphous silicon will stably hold a high photoconductivity. This method is very effective in the production of electrophotographic members because it can simply detect amorphous silicon layers of inferior quality.
Regarding oxygen, it has been reported that, when oxygen is contained in a layer as a result of being added by a reaction gas during the preparation of the amorphous silicon, it contributes to an enhancement of the photoconductivity of the layer (published in, for example, Phys, Rev. Lett., 41, 1492(1978)). However, in this case the oxygen enters from the beginning in a form in which it effectively extinguishes the localized states in the amorphous silicon. Unlike the peaks described above, therefore, the maximum infrared absorption peak value exists in the vicinity of approximately 930 cm l.
Accordingly, such oxygen intentionally added in advance differs from the extrinsic oxygen forming the cause of the characteristics degradation as stated in this invention, and it forms no hindrance to the method of assessment of the amorphous silicon layer of this invention relying on the comparison of peak values.
Although the causes of the peaks are not yet entirely clear, it is presumed that the peak lying principally at 930 cm 1 in the case of intentionally adding oxygen will be a bond in the form of (-Si-0-), while the peaks changing with the lapse of time (at 1,140, 1,040, 650, 860 and 800 cm 1) will be attributed to the bond of sia~.
Known well as methods for forming amorphous silicon containing hydrogen (usually, denoted by a-Si:H) a~e (1) the glow discharge process based on the low-temperature decomposition of monosilane SiH4, (2) the reactive sputtering process in which silicon is sputter-evaporated in an atmosphere containing hydrogen, (3) the ion-plating process, etc.
When forming the layer by any of the various layer-forming methods, the hydrogen content of the amorphous silicon layer can be varied by controlling the substrate temperature, the concentration of hydrogen in the atmosphere or the input power, etc.
With any of the processes, a layer having the best photoelectric conversion characteristics is obtained when the substrate temperature during the formation of the layer is 150 - 250 C. In the case of the glow discharge process, a layer of good photoelectric conversion 15 characteristics has a~s low a resistivity as 106 _ 107 Q .cm and is unsuitable for electrophotography.
Therefore, such a consideration as doping the layer with a slight amount of boron to raise its resistivity is necessary. In contrast, the reactive sputtering process 20 can produce a layer having a resistivity of at least 10l Q .cm, besides good photoelectric conversion characteristics. Moreover~ it ean ~orm a uniform layer of large area by employing a sufficiently large sputtering target. It ean therefore be said to be particularly 25 useful for forming a photoconductive layer for eleetrophotography.
Reaetive sputtering is usually performed by equipment such as shown in Figure 2, wherein numeral 31 designates a bell jar, numeral 32 an evacuating system, numeral 33 a 30 radio-frequency power source, numeral 34 a sputtering target, numeral 35 a substrate holder, and numeral 36 a substrate. Sputtering equipment includes, not only structure designed to perform a sputter-evaporation on a flat substrate as illustrated, but also structure that can 8~2 perform a sputter-evaporation on a cylindrical or drum-shaped substrate, and such alternatives can be employed as required.
Reactive sputtering is carried out by evacuating the bell jar 31, introducing hydrogen and an inert gas such as argon thereinto, and supplying a radio-frequency voltage from the source 33 to cause a discharge,. The quantity of hydrogen contained in a layer so formed is determined principally by the pressure of hydrogen in the atomosphere during discharge. An amorphous silicon layer containing hydrogen in a manner suited to this invention is produced when the hydrogen pressure during sputtering lies in a range of from 5 x 10 5 Torr to ~ x 10 3 Torr.
Further, when the pressure of the gas is kept below 1 x 10 2 Torr, an'amorphous silicon layer of good stability is obtained.
The lower limit of pressure of the gas is determined by maintenance of the discharge, and is approximately 1 x 10 4 Torr when employing magnetron sputtering. For the deposition rate of the layer at this time, a value of 1 A/sec. - 30 A/sec. is preferableO
When preparing an amorphous silicon layer by a reactive,sputtering process, it has been found that a layer liable to change in quality is formed if the pressure o~ the gas during the reaction exceeds a certain value. Figures 3 and 4 show the circumstances, note being , especially taken of the peaks of 1,14~ cm 1 and 1,040 cm lo Figure 3 illustrates samples produced by the conventional reactive sputtering process, while Figure
4 illustrates samples produced by the magnetron sputtering process. It is understood that, even when the magnetron sputtering process is employed, amorphous silicon prepared under a gas pressure higher than 1 x 10 2 Torr changes in quality. The peaks of 1,140 cm 1 and 1,040 cm 1 8~2 indicative of the bond between oxygen and silicon are seen to be large, and the amorphous silicon layer has an unstable quality of easy oxidation. Such an amorphous silicon layer cannot attain the resistivity of at least s 101 ~ .cm required for an electrophotographic member.
The limit of pressure is somewhat dependent upon the equipment. By way of example, with the so-called magnetron type sputtering wherein a magnetic field is appIied to a target to confine a plasma so as to efficiently perform the sputtering reaction, it is possible to form a layer that does not change in quality even at a pressure somewhat higher than with conventional rective sputtering equipment. However, with magnetron sputtering amorphous silicon of good quality cannot be formed under a pressure in excess of 1 x 10 2 Torr as stated above. In a conventional reactive sputtering process, the limit of pressure must be 5 x 10 3 Torr or less.
On the other hand, when the Vickers hardness of an amorphous silicon layer formed by the magnetron type sputtering process was measured, it was found that it increases ~ith a lowering of the pressure, as shown in Figure 5. Moreover, the layer produced by the magnetron t~pe method exhibits a higher hardness than a layer produced by conventional sputtering. The hardness of the layer is considered to directly reflect the denseness of the structure of the amorphous silicon. Considered in relation to the gas pressure and the variations of the infrared absorption peaks, as stated before, it is found that a value of at least 950 kg/mm2 in terms of the Vickers hardness must be exhibited in order to make the amorphous silicon layer good in quality and usable for electrophotography.
As explained above, by specifying the quantity of hydrogen to be contained in the amorphous silicon layer and the optical forbidden band gap of the layer, a layer having a photoconductivity satisfactory for electrophoto-graphy can be realized. By taking note of the infrared absorption peaks of the bond between silicon and oxygen, a layer of good stability and high resistivity can be obtained. Whether or note the amorphous silicon layer is stable enough to endure use can be simply ascertained by measuring the hardness of the layer. By employing these measures in combination, an amorphous silicon photo-conductor layer having good electrophotographic characteristics can be obtained.
Specific examples of an electrophotographic member having an amorphous silicon photoconductor layer ~ill now be described.
Figures 6 and 7 are sectional views of electro-photographic members. They correspnd respectively to a case where the substrate is made of a conductive material such as a metal, and a case where the substrate is made of an insulator. In both figures, the same numerals indicate the same parts.
Numeral 1 designates the substrate, and numeral 2 a photoconductive layer including an amorphous silicon layer. The substrate 1 may be a metal plate, such as aluminum, stainless steel, nichrome9 molybdenum, gold, niobium, tantalum or platinum plate; an organic material such as polyimide resin; glass; ceramics; etc. When the substrate 1 is an electrical insulator, an electrode 11 needs to be deposited thereon, as shown in Figure 7. Used as the electrode is a thin film of a metal material such as aluminum or chromium, or a transparent electrode of an oxide such as SnO2 and In-Sn-0. The photoconductive layer 2 is disposed on the electrode. If the substrate 1 is light-transmissive and the electrode 11 is transparent, light to enter the photoconductive layer 2 may be projected through the substrate 1.
The photoconductive layer 2 can be provided with a layer 21 for suppressing the injection of excess carriers from the substrate side, and a layer 22 for suppressing the injection of charges from the surface side. For the layers 21 and 22, a high-resistivity oxide, sulfide or selenide such as SiO, SiO2, A1203, CeO2, V203, Ta20, As2Se3 and As2S3 are used, or layers of an organic substance such as polyvinyl carbazole are sometimes used~ Although these layers 21 and 22 serve to improve the electrophotographic characteristics of the photoconductive layer of this invention, they are not always essential.
23, 24 and 25 are all layers whose principal constituents are amorphous silicon. The thickness of the amorphous silicon layer is generally 2 ~m - 70 ~m, and often lies in the range of 20 ~m - 40 ~m. Each of the layers 23 and 25 is an amorphous silicon layer that satisfies the characteristics of this invention described above and has a thickness of at least 10 nm. Even if the resisti~ity of the layer 24 is below 101 ~.cm, no bad influence is exerted on the dark decay characteristics of the electrophotographic member due to the presence of the layers 23 and 24. Although, in Figures ~ and 7 the amorphous silicon layer has this three-layered structure, it may of course be a generally uniform amorphous-silicon layer having the same properties as the foregoing surface ~interface) layer. In order to vary the electrical or optical characteristics of amorphous silicon, a\material in which part of the silicon is replaced by car-bon or germanium can also be used for the electrophotographic member. Useful as the quantity of the substitution by germanium or carbon is within 30 atomic-%. Further, the amorphous silicon layer can sometimes be doped with a very small amount of boron or the like, as may be needed.
However, it is necessary for ensuring photoconductivity that at least 50 atomic-% of silicon is contained on the average within the layer.
A protective film or the like can be disposed on the surface of the amorphous silicon photoconductor. Suitable material for this protective film is a synthetic resin such as polyamide and polyethylene terephthalate.
Referring to Figure 8, an embodiment of an electrophotographic plate according to the present invention is formed on the surface of a rotary drum 51.
When the drum 51 is formed of a conductor such as aluminum, the drum 51 per se may be used as the conducting substrate of the electrophotographic member. When a drum of glass or the like is used, a conductor, such as a metal, is coated on the surface of the glass, and a plurality of predetermined amorphous Si layers are laminated thereon. Beams 55 from a light source 52, such as a semiconductor laser, pass through a beam collecting lens 53 and impinge on a polyhedral mirror 54. They are reflected from the mirror 54 to reach the surface of the drum 51.
Charges induced on the drum 51 by a charger 56 are neut~alized by signals imparted to the laser beam to form a latent image. The latent image arrives at a toner station 57 where the toner adheres only to the latent image area irradiated with the laser beam. This toner is transferred onto recording paper 59 at a transfer station
The limit of pressure is somewhat dependent upon the equipment. By way of example, with the so-called magnetron type sputtering wherein a magnetic field is appIied to a target to confine a plasma so as to efficiently perform the sputtering reaction, it is possible to form a layer that does not change in quality even at a pressure somewhat higher than with conventional rective sputtering equipment. However, with magnetron sputtering amorphous silicon of good quality cannot be formed under a pressure in excess of 1 x 10 2 Torr as stated above. In a conventional reactive sputtering process, the limit of pressure must be 5 x 10 3 Torr or less.
On the other hand, when the Vickers hardness of an amorphous silicon layer formed by the magnetron type sputtering process was measured, it was found that it increases ~ith a lowering of the pressure, as shown in Figure 5. Moreover, the layer produced by the magnetron t~pe method exhibits a higher hardness than a layer produced by conventional sputtering. The hardness of the layer is considered to directly reflect the denseness of the structure of the amorphous silicon. Considered in relation to the gas pressure and the variations of the infrared absorption peaks, as stated before, it is found that a value of at least 950 kg/mm2 in terms of the Vickers hardness must be exhibited in order to make the amorphous silicon layer good in quality and usable for electrophotography.
As explained above, by specifying the quantity of hydrogen to be contained in the amorphous silicon layer and the optical forbidden band gap of the layer, a layer having a photoconductivity satisfactory for electrophoto-graphy can be realized. By taking note of the infrared absorption peaks of the bond between silicon and oxygen, a layer of good stability and high resistivity can be obtained. Whether or note the amorphous silicon layer is stable enough to endure use can be simply ascertained by measuring the hardness of the layer. By employing these measures in combination, an amorphous silicon photo-conductor layer having good electrophotographic characteristics can be obtained.
Specific examples of an electrophotographic member having an amorphous silicon photoconductor layer ~ill now be described.
Figures 6 and 7 are sectional views of electro-photographic members. They correspnd respectively to a case where the substrate is made of a conductive material such as a metal, and a case where the substrate is made of an insulator. In both figures, the same numerals indicate the same parts.
Numeral 1 designates the substrate, and numeral 2 a photoconductive layer including an amorphous silicon layer. The substrate 1 may be a metal plate, such as aluminum, stainless steel, nichrome9 molybdenum, gold, niobium, tantalum or platinum plate; an organic material such as polyimide resin; glass; ceramics; etc. When the substrate 1 is an electrical insulator, an electrode 11 needs to be deposited thereon, as shown in Figure 7. Used as the electrode is a thin film of a metal material such as aluminum or chromium, or a transparent electrode of an oxide such as SnO2 and In-Sn-0. The photoconductive layer 2 is disposed on the electrode. If the substrate 1 is light-transmissive and the electrode 11 is transparent, light to enter the photoconductive layer 2 may be projected through the substrate 1.
The photoconductive layer 2 can be provided with a layer 21 for suppressing the injection of excess carriers from the substrate side, and a layer 22 for suppressing the injection of charges from the surface side. For the layers 21 and 22, a high-resistivity oxide, sulfide or selenide such as SiO, SiO2, A1203, CeO2, V203, Ta20, As2Se3 and As2S3 are used, or layers of an organic substance such as polyvinyl carbazole are sometimes used~ Although these layers 21 and 22 serve to improve the electrophotographic characteristics of the photoconductive layer of this invention, they are not always essential.
23, 24 and 25 are all layers whose principal constituents are amorphous silicon. The thickness of the amorphous silicon layer is generally 2 ~m - 70 ~m, and often lies in the range of 20 ~m - 40 ~m. Each of the layers 23 and 25 is an amorphous silicon layer that satisfies the characteristics of this invention described above and has a thickness of at least 10 nm. Even if the resisti~ity of the layer 24 is below 101 ~.cm, no bad influence is exerted on the dark decay characteristics of the electrophotographic member due to the presence of the layers 23 and 24. Although, in Figures ~ and 7 the amorphous silicon layer has this three-layered structure, it may of course be a generally uniform amorphous-silicon layer having the same properties as the foregoing surface ~interface) layer. In order to vary the electrical or optical characteristics of amorphous silicon, a\material in which part of the silicon is replaced by car-bon or germanium can also be used for the electrophotographic member. Useful as the quantity of the substitution by germanium or carbon is within 30 atomic-%. Further, the amorphous silicon layer can sometimes be doped with a very small amount of boron or the like, as may be needed.
However, it is necessary for ensuring photoconductivity that at least 50 atomic-% of silicon is contained on the average within the layer.
A protective film or the like can be disposed on the surface of the amorphous silicon photoconductor. Suitable material for this protective film is a synthetic resin such as polyamide and polyethylene terephthalate.
Referring to Figure 8, an embodiment of an electrophotographic plate according to the present invention is formed on the surface of a rotary drum 51.
When the drum 51 is formed of a conductor such as aluminum, the drum 51 per se may be used as the conducting substrate of the electrophotographic member. When a drum of glass or the like is used, a conductor, such as a metal, is coated on the surface of the glass, and a plurality of predetermined amorphous Si layers are laminated thereon. Beams 55 from a light source 52, such as a semiconductor laser, pass through a beam collecting lens 53 and impinge on a polyhedral mirror 54. They are reflected from the mirror 54 to reach the surface of the drum 51.
Charges induced on the drum 51 by a charger 56 are neut~alized by signals imparted to the laser beam to form a latent image. The latent image arrives at a toner station 57 where the toner adheres only to the latent image area irradiated with the laser beam. This toner is transferred onto recording paper 59 at a transfer station
5~. The transferred image is thermally fixed by a fixing heater 60. Reference numeral 61 represents a cleaner for the drum 51.
An embodiment may be adopted in which a glass cylinder is used as the drum, a transparent conductive layer is formed on the glass cylinder and predetermined amorphous silicon layers are laminated thereon.
In this embodiment, the writing light source may be disposed in the cylindrical drum, the beams being incident from the conductor side of the electrophotographic plate.
Needless to say, applications of the electrophoto-graphic member are not limited to the above-mentioned embodiments.
In the instant specification and appended claims, by the term "electrophotographic member" is meant one that is used for an electrophotographic device, a laser beam printer equipment or the like, in the fields of electrophotography, printing, recording and the like.
Example 1:
With reference to Figure 6, an aluminum cylinder whose surface was mirror-polished was heated at 300C in an oxygen atmosphere for 2 hours, to form an A1203 film 21 on the surface of the cylinder substrate 1. This cylinder was installed in rotary magnetron type sputtering equipment, the interior of which was evacuated to 1 x 10 6 Torr. Thereafter, whllst holding the cylinder at 200C, a mixed gas consisting of neon and hydrogen was introduced at 2 x 10 3 Torr (hydrogen pressure: 30%).
In the mixed atmoshphere, an amorphous silicon layer 3 having a hydrogen content of 19 atomic-%, an optical forbidden band gap of 1.92 eV and a resistivity of 4 x 1011 ~ cm was deposited to a thickness of 20 ~m at a deposition rate of to A/sec by a radio-frequency output of 350 W (13.56 MHz). Thereafter, the resultant cylinder was taken out of the sputtering equipment and installed in vacuum evaporation equipment. While holding the substrate temperature at 80C under a pressure of 2 x 10 6 Torr, an As2Se3 film 22 was evaporated to a thickness of 1,000 A. The cylinder thus prepared was used as an electrophotographic sensitive drum. In this example, the 8~
amorphous silicon layer 3 was a single layer.
The infrared absorption spectrum of the amorphous silicon so obtained was as shown by the curve A in Figure 1. Further, when the electrophotographic member was subjected to corona discharge at 615 kV, an initial potential value held across both the ends of the member was 30 V/l ~m which was very desirable for the electrophoto-graphic member.
On the other hand, an electrophotographic member pro-duced in such a way that an amorphous silicon layer wasformed by employing during sputtering a mixed gas consist-ing of neon and hydrogen and having a pressure of 1 x 10 2 Torr (hydrogen pressure: 30%), was 1 x 102 ~.cm in the resistivity and below 1 V/l ~m in initial potential value for the corona discharge. This comparative example was unfavorable because of the low initial potential value. The infrared absorption spectrum of this latter example was as shown by the curve B in Figure 1.
Figure 9 shows the infrared absorption spectra of samples different from the material referred to in Figure 1~ The sample of curve C was prepared by setting a mixed gas of neon and hydrogen at 2 x 10 3 Torr (hydrogen pressure: 55~), while the sample of curve D was prepared by setting the mixed gas at 1 x 10 2 Torr (hydrogen pressure:
55%). Unlike the example shown in Figure 1, in both the samples of the curves C and D, only an infrared absorption peak at a wave number of 2,100 cm 1 is clear, and a peak at 2,000 cm 1 is hardly noted. In both samples, the hydrogen content was 12 atomic-~, and the band gap was 3~ approximately 1.95 eV.
The sample of curve C can also ensure a satisfactory surface potential, and its characteristics exhibit very small changes versus time and are stable.
In contrast, in the sample of curve D, the infrared absorption peak at a wave number of 1,140 cm 1 attributed to the bond between silicon and oxygen is greater than the peak at a wave number of 2,100 cm 1 attributed to the bond between silicon and hydrogen. This latter sample cannot secure a satisfactory surface potential, and its characteristics exhibit large changes versus time.
Figure 10 compares and illustrates how the samples of curves A and B in Figure 1 and the curves C and D in Figure 9 can ensure surface potentials. Curves a, _, c and d in Figure 10 show the characteristics changes of samples A/ B, C and D, respectively.
After charging each electrophotographic member by a corona discharge at 6.5 kV, its surface potential was measured after lapse of 1 sec. A higher surface potential ; signifies that more charges are held. Values at various times were obtained by keeping the electrophotographic member in air and measuring its surface potential anew after, for example one day. It is understood from Figure lO that the samples according to the present invention exhibit very stable characteristics~
Regarding the extent of dark decay, the samples according to this invention exhibit values of below 10 ~ of the surface potential after 1 sec., whereas the materials in which the peaks appear corresponding with the bond between silicon and oxygen exhibit values of above 30 ~ and cannot be put into practical use.
Stable characteristics could be obtained in the foregoing case where at least one of the peaks in the infrared absorption characteristics having centers at 2,200 cm 1, 1,140 cm 1, 1,040 cm -1, 650 cm 1, 860 cm 1 and 800 cm 1 did not exceed 20 % of the intensity of the greater one between the peaks at wave numbers 2,100 cm 1 and 2,000 cm 1.
3Q~
Example 2:
Likewise to Example 1, an aluminum cylinder was used as a substrate 1~ and it was heat-treated in an oxygen atmosphere to form an A1203 film 21 on the surface of the cylinder to a thickness of 500 A. The cylinder was installed in rotary magnetron type sputtering equipment, the interior of which was evacuated to 1 x 10 6 Torr.
Thereafter, while holding the cylinder at 200C, a mixed gas at 2 x 10 3 Torr consisting of neon and hydrogen was introduced. The hydrogen pressure was 30 %. In this atmosphere, a radio-frequency output of 350 W (13.56 MHz) was applied to the equipment, and a first amorphous silicon layer 23 was formed to a thickness of 10 nm at a deposition rate of approximately 2 A/sec. This amorphous silicon had a hydrogen content of 20 atomic-~, an optical forbidden band gap of 1.95 eV, and a resistivity of 3.5 x 1011 Q.cm, and its infrared absorption spectrum was the curve A in Figure 1.
Subsequently, whilst gradually varying the hydrogen pressure from 30 % to 5 ~ with-the pressure of the mixed gas held at 2 x 10 3 Torr, the deposition of amorphous silicon was continued. After the partial pressure reached 5 %, the quantity of hydrogen was gradually increased and returned to the partial pressure of 30 ~ again. The deposition rate was substantially constant in this hydrogen pressure range, and a region with a varying hydrogen content was achieved approximately 25 nm thick by performing the above operations in 2 minutes. In this region (second layer 2~), the part deposited under the condition of a hydrogen pressure of 5 % assumed a hydrogen content of 10 atomic-~, a minimum forbidden band gap of 1.5 eV and a minimum resistivity of 5 x 109 Q .cm, and the first and last parts assumed the same values as the first layer. In the infrared spectrum of the second layer, the peak attributed to the Si-0 bond was not observed as in that of the first layer.
Thereafter, a third amorphous silicon layer was deposited to a thickness of 25 ~m under the same conditions as those of the Eirst layer. When the cylinder thus formed was used as an electrophotographic sensitive drum, a potential of 600 V could be held after corona charging, due to the high resistivities of the first and third layers, and a semiconductor laser source of 7,500 A
could be used due to the second layer.
An embodiment may be adopted in which a glass cylinder is used as the drum, a transparent conductive layer is formed on the glass cylinder and predetermined amorphous silicon layers are laminated thereon.
In this embodiment, the writing light source may be disposed in the cylindrical drum, the beams being incident from the conductor side of the electrophotographic plate.
Needless to say, applications of the electrophoto-graphic member are not limited to the above-mentioned embodiments.
In the instant specification and appended claims, by the term "electrophotographic member" is meant one that is used for an electrophotographic device, a laser beam printer equipment or the like, in the fields of electrophotography, printing, recording and the like.
Example 1:
With reference to Figure 6, an aluminum cylinder whose surface was mirror-polished was heated at 300C in an oxygen atmosphere for 2 hours, to form an A1203 film 21 on the surface of the cylinder substrate 1. This cylinder was installed in rotary magnetron type sputtering equipment, the interior of which was evacuated to 1 x 10 6 Torr. Thereafter, whllst holding the cylinder at 200C, a mixed gas consisting of neon and hydrogen was introduced at 2 x 10 3 Torr (hydrogen pressure: 30%).
In the mixed atmoshphere, an amorphous silicon layer 3 having a hydrogen content of 19 atomic-%, an optical forbidden band gap of 1.92 eV and a resistivity of 4 x 1011 ~ cm was deposited to a thickness of 20 ~m at a deposition rate of to A/sec by a radio-frequency output of 350 W (13.56 MHz). Thereafter, the resultant cylinder was taken out of the sputtering equipment and installed in vacuum evaporation equipment. While holding the substrate temperature at 80C under a pressure of 2 x 10 6 Torr, an As2Se3 film 22 was evaporated to a thickness of 1,000 A. The cylinder thus prepared was used as an electrophotographic sensitive drum. In this example, the 8~
amorphous silicon layer 3 was a single layer.
The infrared absorption spectrum of the amorphous silicon so obtained was as shown by the curve A in Figure 1. Further, when the electrophotographic member was subjected to corona discharge at 615 kV, an initial potential value held across both the ends of the member was 30 V/l ~m which was very desirable for the electrophoto-graphic member.
On the other hand, an electrophotographic member pro-duced in such a way that an amorphous silicon layer wasformed by employing during sputtering a mixed gas consist-ing of neon and hydrogen and having a pressure of 1 x 10 2 Torr (hydrogen pressure: 30%), was 1 x 102 ~.cm in the resistivity and below 1 V/l ~m in initial potential value for the corona discharge. This comparative example was unfavorable because of the low initial potential value. The infrared absorption spectrum of this latter example was as shown by the curve B in Figure 1.
Figure 9 shows the infrared absorption spectra of samples different from the material referred to in Figure 1~ The sample of curve C was prepared by setting a mixed gas of neon and hydrogen at 2 x 10 3 Torr (hydrogen pressure: 55~), while the sample of curve D was prepared by setting the mixed gas at 1 x 10 2 Torr (hydrogen pressure:
55%). Unlike the example shown in Figure 1, in both the samples of the curves C and D, only an infrared absorption peak at a wave number of 2,100 cm 1 is clear, and a peak at 2,000 cm 1 is hardly noted. In both samples, the hydrogen content was 12 atomic-~, and the band gap was 3~ approximately 1.95 eV.
The sample of curve C can also ensure a satisfactory surface potential, and its characteristics exhibit very small changes versus time and are stable.
In contrast, in the sample of curve D, the infrared absorption peak at a wave number of 1,140 cm 1 attributed to the bond between silicon and oxygen is greater than the peak at a wave number of 2,100 cm 1 attributed to the bond between silicon and hydrogen. This latter sample cannot secure a satisfactory surface potential, and its characteristics exhibit large changes versus time.
Figure 10 compares and illustrates how the samples of curves A and B in Figure 1 and the curves C and D in Figure 9 can ensure surface potentials. Curves a, _, c and d in Figure 10 show the characteristics changes of samples A/ B, C and D, respectively.
After charging each electrophotographic member by a corona discharge at 6.5 kV, its surface potential was measured after lapse of 1 sec. A higher surface potential ; signifies that more charges are held. Values at various times were obtained by keeping the electrophotographic member in air and measuring its surface potential anew after, for example one day. It is understood from Figure lO that the samples according to the present invention exhibit very stable characteristics~
Regarding the extent of dark decay, the samples according to this invention exhibit values of below 10 ~ of the surface potential after 1 sec., whereas the materials in which the peaks appear corresponding with the bond between silicon and oxygen exhibit values of above 30 ~ and cannot be put into practical use.
Stable characteristics could be obtained in the foregoing case where at least one of the peaks in the infrared absorption characteristics having centers at 2,200 cm 1, 1,140 cm 1, 1,040 cm -1, 650 cm 1, 860 cm 1 and 800 cm 1 did not exceed 20 % of the intensity of the greater one between the peaks at wave numbers 2,100 cm 1 and 2,000 cm 1.
3Q~
Example 2:
Likewise to Example 1, an aluminum cylinder was used as a substrate 1~ and it was heat-treated in an oxygen atmosphere to form an A1203 film 21 on the surface of the cylinder to a thickness of 500 A. The cylinder was installed in rotary magnetron type sputtering equipment, the interior of which was evacuated to 1 x 10 6 Torr.
Thereafter, while holding the cylinder at 200C, a mixed gas at 2 x 10 3 Torr consisting of neon and hydrogen was introduced. The hydrogen pressure was 30 %. In this atmosphere, a radio-frequency output of 350 W (13.56 MHz) was applied to the equipment, and a first amorphous silicon layer 23 was formed to a thickness of 10 nm at a deposition rate of approximately 2 A/sec. This amorphous silicon had a hydrogen content of 20 atomic-~, an optical forbidden band gap of 1.95 eV, and a resistivity of 3.5 x 1011 Q.cm, and its infrared absorption spectrum was the curve A in Figure 1.
Subsequently, whilst gradually varying the hydrogen pressure from 30 % to 5 ~ with-the pressure of the mixed gas held at 2 x 10 3 Torr, the deposition of amorphous silicon was continued. After the partial pressure reached 5 %, the quantity of hydrogen was gradually increased and returned to the partial pressure of 30 ~ again. The deposition rate was substantially constant in this hydrogen pressure range, and a region with a varying hydrogen content was achieved approximately 25 nm thick by performing the above operations in 2 minutes. In this region (second layer 2~), the part deposited under the condition of a hydrogen pressure of 5 % assumed a hydrogen content of 10 atomic-~, a minimum forbidden band gap of 1.5 eV and a minimum resistivity of 5 x 109 Q .cm, and the first and last parts assumed the same values as the first layer. In the infrared spectrum of the second layer, the peak attributed to the Si-0 bond was not observed as in that of the first layer.
Thereafter, a third amorphous silicon layer was deposited to a thickness of 25 ~m under the same conditions as those of the Eirst layer. When the cylinder thus formed was used as an electrophotographic sensitive drum, a potential of 600 V could be held after corona charging, due to the high resistivities of the first and third layers, and a semiconductor laser source of 7,500 A
could be used due to the second layer.
Claims (7)
l. An electrophotographic member having at least a supporting and a photoconductor layer which is principally formed of amorphous silicon; characterized in that said amorphous silicon contains at least 50 atomic-% of silicon and at least 1 atomic-% of hydrogen as an average within said layer, and that a part which is at least 10 nm thick from a surface or/an interface of said photoconductor layer towards the interior of said photoconductor layer has a hydrogen content in a range of at least 1 atomic-%
to at most 40 atomic-% and an optical forbidden band gap in a range of at least 1.3 eV to at most 2.5 eV and also has the property that the intensity of at least one of peaks having centers at wave numbers of approximately 2,200 cm-1, approximately 1,140 cm-1, approximately
1,040 cm-1, approximately 650 cm-1, approximately 860 cm-1 and approximately 800 cm-1 in an infrared absorption spectrum attributed to a bond between silicon and oxygen does not exceed 20 % of that of a higher one of peaks having centers at wave numbers of approximately 2,000 cm-1 and approximately 2,100 cm-1 attributed to a bond between silicon and hydrogen.
2. An electrophotographic member according to claim 1, wherein said amorphous silicon layer contains at least one element selected from the group consisting of germanium and carbon.
3. An electrophotographic member according to claim 1 or claim 2, wherein said amorphous silicon layer consists of at least three layers, and each of a top layer and a bottom layer of said at least three layers is at least 10 nm thick and has the same hydrogen content, optical forbidden band gap and property as those of said part.
4. An electrophotographic member according to claim 1, wherein said part has a resistivity of at least 1010 .OMEGA..cm.
5. An electrophotographic member according to claim 1, wherein said amorphous silicon layer is formed by a reactive sputtering process in an atmosphere containing hydrogen.
6. An electrophotographic member according to claim 1, wherein said photoconductor layer is provided with a protective film disposed on a surface thereof, said protective film being formed of a snythetic resin.
7. An electrophotographic member according to claim 6, wherein said synthetic resin comprises polyamide or polyethylene terephthalate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP102530/1980 | 1980-07-28 | ||
| JP10253080A JPS5727263A (en) | 1980-07-28 | 1980-07-28 | Electrophotographic photosensitive film |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1152802A true CA1152802A (en) | 1983-08-30 |
Family
ID=14329854
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000382318A Expired CA1152802A (en) | 1980-07-28 | 1981-07-23 | Electrophotographic member including a layer of amorphous silicon containing hydrogen |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4365013A (en) |
| EP (1) | EP0045204B1 (en) |
| JP (1) | JPS5727263A (en) |
| CA (1) | CA1152802A (en) |
| DE (1) | DE3167074D1 (en) |
Families Citing this family (60)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4484809B1 (en) * | 1977-12-05 | 1995-04-18 | Plasma Physics Corp | Glow discharge method and apparatus and photoreceptor devices made therewith |
| US4394425A (en) * | 1980-09-12 | 1983-07-19 | Canon Kabushiki Kaisha | Photoconductive member with α-Si(C) barrier layer |
| US4394426A (en) * | 1980-09-25 | 1983-07-19 | Canon Kabushiki Kaisha | Photoconductive member with α-Si(N) barrier layer |
| IE53485B1 (en) * | 1981-02-12 | 1988-11-23 | Energy Conversion Devices Inc | Improved photoresponsive amorphous alloys |
| US4409311A (en) * | 1981-03-25 | 1983-10-11 | Minolta Camera Kabushiki Kaisha | Photosensitive member |
| US4423133A (en) * | 1981-11-17 | 1983-12-27 | Canon Kabushiki Kaisha | Photoconductive member of amorphous silicon |
| JPS58189643A (en) * | 1982-03-31 | 1983-11-05 | Minolta Camera Co Ltd | Photoreceptor |
| US4491626A (en) * | 1982-03-31 | 1985-01-01 | Minolta Camera Kabushiki Kaisha | Photosensitive member |
| US4490450A (en) * | 1982-03-31 | 1984-12-25 | Canon Kabushiki Kaisha | Photoconductive member |
| DE3311835A1 (en) * | 1982-03-31 | 1983-10-13 | Canon K.K., Tokyo | Photoconductive recording element |
| JPS58192044A (en) * | 1982-05-06 | 1983-11-09 | Konishiroku Photo Ind Co Ltd | Photoreceptor |
| JPS5957416A (en) * | 1982-09-27 | 1984-04-03 | Konishiroku Photo Ind Co Ltd | Formation of compound semiconductor layer |
| US4617246A (en) * | 1982-11-04 | 1986-10-14 | Canon Kabushiki Kaisha | Photoconductive member of a Ge-Si layer and Si layer |
| US4569894A (en) * | 1983-01-14 | 1986-02-11 | Canon Kabushiki Kaisha | Photoconductive member comprising germanium atoms |
| US4532198A (en) * | 1983-05-09 | 1985-07-30 | Canon Kabushiki Kaisha | Photoconductive member |
| US4513073A (en) * | 1983-08-18 | 1985-04-23 | Minnesota Mining And Manufacturing Company | Layered photoconductive element |
| JPS6083957A (en) * | 1983-10-13 | 1985-05-13 | Sharp Corp | Electrophotographic sensitive body |
| US4544617A (en) * | 1983-11-02 | 1985-10-01 | Xerox Corporation | Electrophotographic devices containing overcoated amorphous silicon compositions |
| JPS60243663A (en) * | 1984-05-18 | 1985-12-03 | Kyocera Corp | Electrophotographic sensitive body |
| JPS6126054A (en) * | 1984-07-16 | 1986-02-05 | Minolta Camera Co Ltd | Electrophotographic sensitive body |
| US4613556A (en) * | 1984-10-18 | 1986-09-23 | Xerox Corporation | Heterogeneous electrophotographic imaging members of amorphous silicon and silicon oxide |
| US5753542A (en) | 1985-08-02 | 1998-05-19 | Semiconductor Energy Laboratory Co., Ltd. | Method for crystallizing semiconductor material without exposing it to air |
| US5962869A (en) * | 1988-09-28 | 1999-10-05 | Semiconductor Energy Laboratory Co., Ltd. | Semiconductor material and method for forming the same and thin film transistor |
| DE3681655D1 (en) * | 1985-08-03 | 1991-10-31 | Matsushita Electric Ind Co Ltd | Elektrophotographischer photorezeptor. |
| US4738912A (en) * | 1985-09-13 | 1988-04-19 | Minolta Camera Kabushiki Kaisha | Photosensitive member having an amorphous carbon transport layer |
| US4749636A (en) * | 1985-09-13 | 1988-06-07 | Minolta Camera Kabushiki Kaisha | Photosensitive member with hydrogen-containing carbon layer |
| US4743522A (en) * | 1985-09-13 | 1988-05-10 | Minolta Camera Kabushiki Kaisha | Photosensitive member with hydrogen-containing carbon layer |
| US4741982A (en) * | 1985-09-13 | 1988-05-03 | Minolta Camera Kabushiki Kaisha | Photosensitive member having undercoat layer of amorphous carbon |
| US5166018A (en) * | 1985-09-13 | 1992-11-24 | Minolta Camera Kabushiki Kaisha | Photosensitive member with hydrogen-containing carbon layer |
| US4777103A (en) * | 1985-10-30 | 1988-10-11 | Fujitsu Limited | Electrophotographic multi-layered photosensitive member having a top protective layer of hydrogenated amorphous silicon carbide and method for fabricating the same |
| JPS62170968A (en) * | 1986-01-23 | 1987-07-28 | Hitachi Ltd | Amorphous silicon electrophotographic sensitive body and its production |
| US5000831A (en) * | 1987-03-09 | 1991-03-19 | Minolta Camera Kabushiki Kaisha | Method of production of amorphous hydrogenated carbon layer |
| DE3717727A1 (en) * | 1987-05-26 | 1988-12-08 | Licentia Gmbh | ELECTROPHOTOGRAPHIC RECORDING MATERIAL AND METHOD FOR THE PRODUCTION THEREOF |
| DE3832453A1 (en) * | 1987-09-25 | 1989-04-06 | Minolta Camera Kk | PHOTO-SENSITIVE ELEMENT |
| US5152833A (en) * | 1989-08-31 | 1992-10-06 | Sanyo Electric Co., Ltd. | Amorphous silicon film, its production and photo semiconductor device utilizing such a film |
| US5210050A (en) * | 1990-10-15 | 1993-05-11 | Semiconductor Energy Laboratory Co., Ltd. | Method for manufacturing a semiconductor device comprising a semiconductor film |
| US7115902B1 (en) | 1990-11-20 | 2006-10-03 | Semiconductor Energy Laboratory Co., Ltd. | Electro-optical device and method for manufacturing the same |
| KR950013784B1 (en) | 1990-11-20 | 1995-11-16 | 가부시키가이샤 한도오따이 에네루기 겐큐쇼 | Field effect trasistor and its making method and tft |
| US5849601A (en) | 1990-12-25 | 1998-12-15 | Semiconductor Energy Laboratory Co., Ltd. | Electro-optical device and method for manufacturing the same |
| KR950001360B1 (en) * | 1990-11-26 | 1995-02-17 | 가부시키가이샤 한도오따이 에네루기 겐큐쇼 | Electric optical device and driving method thereof |
| US7154147B1 (en) * | 1990-11-26 | 2006-12-26 | Semiconductor Energy Laboratory Co., Ltd. | Electro-optical device and driving method for the same |
| US8106867B2 (en) | 1990-11-26 | 2012-01-31 | Semiconductor Energy Laboratory Co., Ltd. | Electro-optical device and driving method for the same |
| US7098479B1 (en) | 1990-12-25 | 2006-08-29 | Semiconductor Energy Laboratory Co., Ltd. | Electro-optical device and method for manufacturing the same |
| US7576360B2 (en) | 1990-12-25 | 2009-08-18 | Semiconductor Energy Laboratory Co., Ltd. | Electro-optical device which comprises thin film transistors and method for manufacturing the same |
| EP0499979A3 (en) | 1991-02-16 | 1993-06-09 | Semiconductor Energy Laboratory Co., Ltd. | Electro-optical device |
| JP2794499B2 (en) * | 1991-03-26 | 1998-09-03 | 株式会社半導体エネルギー研究所 | Method for manufacturing semiconductor device |
| US5234748A (en) * | 1991-06-19 | 1993-08-10 | Ford Motor Company | Anti-reflective transparent coating with gradient zone |
| JP2845303B2 (en) * | 1991-08-23 | 1999-01-13 | 株式会社 半導体エネルギー研究所 | Semiconductor device and manufacturing method thereof |
| JP2830666B2 (en) * | 1991-11-29 | 1998-12-02 | 日本電気株式会社 | Method for forming a light emitting layer on a semiconductor |
| US6693681B1 (en) | 1992-04-28 | 2004-02-17 | Semiconductor Energy Laboratory Co., Ltd. | Electro-optical device and method of driving the same |
| JP2814161B2 (en) | 1992-04-28 | 1998-10-22 | 株式会社半導体エネルギー研究所 | Active matrix display device and driving method thereof |
| US6022458A (en) * | 1992-12-07 | 2000-02-08 | Canon Kabushiki Kaisha | Method of production of a semiconductor substrate |
| EP0603585B1 (en) * | 1992-12-21 | 2000-02-09 | Balzers Aktiengesellschaft | Optical element, method of fabricating a coating, coating or coating system and use of the optical element |
| US7081938B1 (en) | 1993-12-03 | 2006-07-25 | Semiconductor Energy Laboratory Co., Ltd. | Electro-optical device and method for manufacturing the same |
| EP0679955B9 (en) * | 1994-04-27 | 2005-01-12 | Canon Kabushiki Kaisha | Electrophotographic light-receiving member and process for its production |
| JP2900229B2 (en) | 1994-12-27 | 1999-06-02 | 株式会社半導体エネルギー研究所 | Semiconductor device, manufacturing method thereof, and electro-optical device |
| US5834327A (en) | 1995-03-18 | 1998-11-10 | Semiconductor Energy Laboratory Co., Ltd. | Method for producing display device |
| FR2764309B1 (en) * | 1997-06-06 | 1999-08-27 | Corning Inc | PROCESS FOR CREATING A SILICON LAYER ON A SURFACE |
| WO2018094000A1 (en) * | 2016-11-18 | 2018-05-24 | Applied Materials, Inc. | Methods for depositing amorphous silicon layers or silicon oxycarbide layers via physical vapor deposition |
| JP7019350B2 (en) * | 2017-09-01 | 2022-02-15 | キヤノン株式会社 | Electrophotographic photosensitive member |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2746967C2 (en) * | 1977-10-19 | 1981-09-24 | Siemens AG, 1000 Berlin und 8000 München | Electrophotographic recording drum |
| US4265991A (en) * | 1977-12-22 | 1981-05-05 | Canon Kabushiki Kaisha | Electrophotographic photosensitive member and process for production thereof |
| GB2018446B (en) * | 1978-03-03 | 1983-02-23 | Canon Kk | Image-forming member for electrophotography |
| JPS554040A (en) * | 1978-06-26 | 1980-01-12 | Hitachi Ltd | Photoconductive material |
| JPS5562778A (en) * | 1978-11-02 | 1980-05-12 | Fuji Photo Film Co Ltd | Preparation of photoconductor film |
| JPS5591885A (en) * | 1978-12-28 | 1980-07-11 | Canon Inc | Amorphous silicon hydride photoconductive layer |
| US4226643A (en) * | 1979-07-16 | 1980-10-07 | Rca Corporation | Method of enhancing the electronic properties of an undoped and/or N-type hydrogenated amorphous silicon film |
| JPS56146142A (en) * | 1980-04-16 | 1981-11-13 | Hitachi Ltd | Electrophotographic sensitive film |
-
1980
- 1980-07-28 JP JP10253080A patent/JPS5727263A/en active Pending
-
1981
- 1981-07-23 CA CA000382318A patent/CA1152802A/en not_active Expired
- 1981-07-24 EP EP81303422A patent/EP0045204B1/en not_active Expired
- 1981-07-24 DE DE8181303422T patent/DE3167074D1/en not_active Expired
- 1981-07-28 US US06/287,633 patent/US4365013A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5727263A (en) | 1982-02-13 |
| EP0045204A2 (en) | 1982-02-03 |
| US4365013A (en) | 1982-12-21 |
| DE3167074D1 (en) | 1984-12-13 |
| EP0045204B1 (en) | 1984-11-07 |
| EP0045204A3 (en) | 1982-02-24 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |