WO2013004923A1 - Method for producing a homojunction photovoltaic cell comprising a passivation thin film made from crystalline silicon oxide - Google Patents

Method for producing a homojunction photovoltaic cell comprising a passivation thin film made from crystalline silicon oxide Download PDF

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Publication number
WO2013004923A1
WO2013004923A1 PCT/FR2012/000266 FR2012000266W WO2013004923A1 WO 2013004923 A1 WO2013004923 A1 WO 2013004923A1 FR 2012000266 W FR2012000266 W FR 2012000266W WO 2013004923 A1 WO2013004923 A1 WO 2013004923A1
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substrate
thin film
silicon oxide
crystalline silicon
surface oxidation
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PCT/FR2012/000266
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French (fr)
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Yannick Veschetti
Pierre Mur
Hubert Moriceau
Pierre-Jean Ribeyron
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Commissariat à l'Energie Atomique et aux Energies Alternatives
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Publication of WO2013004923A1 publication Critical patent/WO2013004923A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/186—Particular post-treatment for the devices, e.g. annealing, impurity gettering, short-circuit elimination, recrystallisation
    • H01L31/1868—Passivation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0216—Coatings
    • H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/02167—Coatings for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0236—Special surface textures
    • H01L31/02363—Special surface textures of the semiconductor body itself, e.g. textured active layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier
    • H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/547—Monocrystalline silicon PV cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the invention relates to a method for producing a homojunction photovoltaic cell comprising a crystalline silicon substrate provided with two faces, respectively front and rear, of two main regions having opposite doping types, and comprising a crystalline oxide thin film. of silicon arranged directly on one of the two faces of the substrate.
  • a homojunction photovoltaic cell comprises a junction formed in the same semiconductor material and for directly converting the received photons into an electrical signal.
  • the homojunction is, in particular, formed in a crystalline silicon substrate comprising two regions having opposite doping types (n and p). More particularly, this can be obtained from a silicon substrate having a given type of doping (for example n-type doping) and in which a doped zone is formed according to a type of opposite doping (for example doping of type p).
  • This doped zone commonly called emitter, is generally formed from the front face of the substrate, corresponding in principle to the face of the substrate for receiving solar radiation.
  • the conversion efficiency of the homojunction photovoltaic cells is generally limited by losses at the front and / or rear faces of the substrate by recombination. It is known to minimize these surface recombinations by integrating a passivation layer of dielectric material, intended to reduce the interface states or to create a favorable field effect to repel the charge carriers to the junction, where they must be collected. Different dielectrics are commonly used in the field of homojunction photovoltaic cells.
  • thermal oxide S1O2 is that its realization remains expensive. This is therefore not compatible with a process for producing low cost industrial photovoltaic cells. In addition, the passivation of the surfaces is not optimal. Object of the invention
  • the object of the invention is to propose a process for producing a homojunction photovoltaic cell having good surface passivation, while being inexpensive.
  • FIG. 1 shows schematically and in section, a particular embodiment of a homojunction photovoltaic cell according to the invention.
  • FIGS. 2 and 3 show, schematically and in section, first and second embodiments of the photovoltaic cell according to Figure 1.
  • a homojunction photovoltaic cell comprises a substrate 1 made of crystalline silicon. This includes in particular:
  • the second main region 3 surmounting the first main region 2 and having a doping type opposite to that of the first main region 2.
  • the second main region 3, also called emitter of the homojunction photovoltaic cell may advantageously be formed in the upper part of the substrate 1, on the front face 1a of the substrate 1.
  • the face before 1a of the substrate 1 formed in the second main region 3 is, in Figure 1, textured (or structured) to increase the optical confinement of the cell.
  • the texturing can be performed, conventionally in the field of photovoltaic cells, in the form of pyramids.
  • the front face 1a of the substrate 1 could also be a chemically polished surface, for example according to conventional surface preparation techniques in the photovoltaic field, such as etching in a chemical bath, for example, based on concentrated KOH.
  • the rear face 1b of the substrate 1 can also be a textured surface, for example in the form of pyramids, or be a polished surface.
  • a chemical polishing of the rear face 1b it can be achieved by etching in a bath comprising a solution comprising HF, HNO 3 and H 2 O 2, in proportions 1: 3: 3.
  • the substrate 1 may also comprise, on the rear face 1b of the substrate 1, a third region 4 exhibiting a type of doping enabling the formation of a field on the substrate. rear interface, also known by the acronym BSF ("Back Surface Field").
  • BSF Back Surface Field
  • the third region 4 is in direct contact with the first main region 2. It presents, advantageously, doping of the same type as that of the first main region 2.
  • the substrate 1 may be a crystalline silicon substrate comprising a first n-doped main region 2.
  • the second region 3 or emitter of the substrate 1 has, then, a doping of the opposite type, p or p +.
  • the second region 3 is, for example, obtained by a boron diffusion operation in the substrate 1, from the front face 1a of the substrate 1. Such an operation makes it possible to obtain, locally and on the surface, a p + type doping.
  • a phosphorus diffusion operation, from the rear face 1b of the substrate 1 can advantageously be carried out to form the third region 4 (or BSF) of the substrate 1, with n + doping.
  • the photovoltaic cell also comprises at least one thin film of crystalline silicon oxide 5, arranged directly on one of the front or rear faces of the substrate.
  • This crystalline silicon oxide thin film 5 is intended to allow the passivation of said substrate face.
  • the crystalline silicon oxide thin film 5 is disposed directly on the front face 1a of the substrate 1. It is thus in direct contact with the second main region 3 of the substrate.
  • the oxide thin film Silicon crystalline 5 makes it possible to passivate the emitter in silicon doped with boron.
  • the thin film 5 is crystalline silicon oxide, that is to say an oxide in crystalline form.
  • the crystalline form of the silicon oxide could be, in some cases, the tridymite form for a silicon substrate having a crystallographic plane (100).
  • the silicon crystalline oxide thin film 5 advantageously has a thickness greater than or equal to 2 nanometers and less than or equal to 20 nanometers and, preferably, a thickness greater than or equal to 5 nanometers and less than or equal to 10 nanometers.
  • the crystalline silicon oxide thin film 5 may have a thickness of 8 nm.
  • Such a thin film 5 is, more particularly, a thin film obtained by oxidizing the silicon of a surface portion of the substrate 1.
  • the superficial portion of the substrate 1 is meant an area of the substrate 1 extending from a free surface of the substrate 1 and in particular from one of the front faces 1a or rear 1b of the substrate 1, towards the inside thereof, over a very small thickness (advantageously less than 20 nm).
  • the oxidation allowing the formation of the thin film 5 is a radical surface oxidation, that is to say an oxidation carried out by means of radicals (or free radicals).
  • radicals are in particular oxygen radicals, for example obtained from oxygen, ozone and / or water. The radicals thus obtained oxidize, then, the silicon on a superficial part of the substrate 1.
  • the silicon oxide thus obtained during the radical oxidation is at least partly in a crystalline form.
  • the radical surface oxidation of the silicon substrate is advantageously controlled to allow the formation of a thin film of silicon oxide in a crystalline form in direct contact with a surface of the silicon substrate. Radical surface oxidation of the substrate can however, in some cases, lead to the additional formation on the crystalline silicon oxide of silicon oxide in amorphous form.
  • the crystalline silicon oxide thin film and the optional layer of amorphous silicon oxide are thus formed in a single step consisting of a radical surface oxidation of a surface of the substrate.
  • the crystalline silicon oxide forming the thin film 5 remains interposed between the substrate 1 and the amorphous silicon oxide.
  • the amorphous silicon oxide, advantageously formed during the radical surface oxidation may optionally be removed by pickling, during a specific step following the radical surface oxidation and, more particularly, before the formation of a possible anti-reflection layer.
  • the oxidation is advantageously assisted by means of a plasma or by the application of ultraviolet radiation to the surface of the substrate to be oxidized.
  • the plasma or ultraviolet radiation treatment facilitates, in particular, the formation of free radicals used to oxidize the silicon of the substrate 1. They are, more particularly, de ' , O 2 ' and / or OH ' type radicals, according to the type of treatment and are in particular obtained from oxygen and / or ozone and / or water.
  • the oxidation of the superficial portion of the substrate 1 can be carried out using oxygen and ultraviolet radiation having a wavelength range of between 160 nm and 400 nm.
  • the wavelengths of ultraviolet radiation used are, for example, about 185 nm and about 254 nm.
  • the oxygen under the action of ultraviolet radiation, dissociates into free radicals O ' and ozone. Free radicals can oxidize the silicon surface.
  • the temperature during the oxidation operation may range from room temperature to about 900 ° C.
  • the step of producing the crystalline silicon oxide thin film is advantageously carried out at a temperature below 800 ° C.
  • the temperature is between 20 ° C and 400 ° C, especially during a radical oxidation from ultraviolet radiation and ozone.
  • the temperature during the oxidation step radical is the ambient temperature.
  • ambient temperature is meant, in general, a temperature between 20 ° C and 50 ° C.
  • the diffusion profiles of the transmitter and the BSF are not redistributed.
  • the transmitter especially when it is a boron doped transmitter does not undergo strong depletion on the surface, which represents an advantage in terms of surface passivation.
  • the pressure may be between about 10 -4 and about 10 5 Pa, and preferably the oxidation step is carried out at ambient pressure. of the order of 1atm, or 1013.25 hPa.
  • the temperature and the pressure of the crystalline silicon oxide thin film forming operation are respectively room temperature and ambient pressure.
  • the photovoltaic cell may comprise one or more anti-reflection layers. It may be a SiN layer, deposited by plasma-assisted chemical vapor deposition (PECVD), at the front face 1a and / or the rear face 1b of the substrate 1 for an action antireflection and accentuated passivation of surfaces.
  • PECVD plasma-assisted chemical vapor deposition
  • Such an antireflection layer typically has a thickness between 60nm and 80nm .
  • FIG. 2 illustrates an embodiment of a photovoltaic cell comprising, in addition to the elements represented in FIG. 1, an anti-reflection layer 6 disposed directly on the crystalline silicon oxide thin film 5 and an anti-reflection layer 7 arranged directly on the rear face 1b of the substrate 1.
  • contacts are more particularly made in the form of a grid on both front and rear faces of the substrate to collect the photogenerated current.
  • These contacts can be made by screen printing, by electrodeposition, by evaporation, ... If we use a Screen printing of a suitable paste, an infrared annealing allows to perforate the anti-reflection layers to reach the junction.
  • FIG. 3 illustrates, thus, an embodiment of a photovoltaic cell, comprising in addition to the elements represented in FIG. 2, such contacts 8.
  • the crystalline silicon oxide thin film is in direct contact on one of the two faces of the substrate, and more particularly on the whole of said face.
  • the crystalline silicon oxide film of the photovoltaic cell is always in direct contact on one of the two faces of the substrate, and more particularly on the whole of said face, that is to say that the silicon crystalline oxide thin film serving as a passivation layer is, for example, not etched during the formation of the contacts.
  • the examples above illustrate the production of a silicon crystalline oxide thin film on the front face of a crystalline silicon substrate of a homojunction photovoltaic cell.
  • the silicon crystalline oxide thin film or an additional silicon crystalline oxide thin film may also be disposed directly on the back side of the substrate.
  • the substrate may be a p-type crystalline silicon substrate, in which is formed a doped region on the front face 1 forming an n + doped emitter (for example by phosphor diffusion from the front face).
  • the substrate may also comprise on the rear face a p + doped region (BSF) or an undoped region.
  • BSF p + doped region
  • the silicon crystalline oxide thin film is formed at the back side to promote surface passivation.
  • SiN anti-reflection layers can then be deposited on the front face and / or rear face of the substrate and the contacts are also in grid form.
  • FIG. 3 illustrates a case where the photovoltaic cell comprises an anti-reflection layer for each of the faces before 1a and rear 1b of the substrate 1
  • the front and rear faces of a photovoltaic cell according to the invention may or may not be covered with an anti-reflection layer.
  • the production of a silicon crystalline oxide thin film can be applied to any type of homojunction photovoltaic cell architecture.

Abstract

The invention relates to a method for producing a homojunction photovoltaic cell comprising at least one thin film (5) of crystalline silicon oxide placed directly on a front surface (1a) or rear surface (1b) of a substrate (1) of crystalline silicon. The thin film (5) is intended to allow passivation of said surface (1a, 1b) of the substrate (1). The thin film (5) of crystalline silicon oxide is advantageously placed directly on the front surface (1a) of the substrate, said surface forming the interface between the thin film (5) of crystalline silicon oxide and one of two regions (2, 3) of opposite doping type forming the homojunction in the substrate (1). More particularly, the thin film (11) is obtained by free-radical oxidation of a surface portion of the substrate (1). In addition, the photovoltaic cell can advantageously comprise an anti-reflection layer (6, 7) on the front surface (1a) and/or the back surface (1b) of the substrate (1).

Description

Procédé de réalisation d'une cellule photovoltaïque à homojonction comprenant un film mince de passivation en oxyde cristallin de silicium. Domaine technique de l'invention  Process for producing a homojunction photovoltaic cell comprising a thin passivation film made of crystalline silicon oxide. Technical field of the invention
L'invention concerne un procédé de réalisation d'une cellule photovoltaïque à homojonction comprenant un substrat en silicium cristallin muni de deux faces, respectivement avant et arrière, de deux régions principales présentant des types de dopage opposés, et comprenant un film mince en oxyde cristallin de silicium disposé directement sur une des deux faces du substrat. The invention relates to a method for producing a homojunction photovoltaic cell comprising a crystalline silicon substrate provided with two faces, respectively front and rear, of two main regions having opposite doping types, and comprising a crystalline oxide thin film. of silicon arranged directly on one of the two faces of the substrate.
État de la technique State of the art
Une cellule photovoltaïque à homojonction comporte une jonction formée dans un même matériau semi-conducteur et permettant de convertir directement les photons reçus en un signal électrique. L'homojonction est, en particulier, formée dans un substrat en silicium cristallin comprenant deux régions ayant des types de dopage opposés (n et p). Plus particulièrement, celle-ci peut être obtenue à partir d'un substrat en silicium présentant un type de dopage donné (par exemple dopage de type n) et dans lequel est formée une zone dopée selon un type de dopage opposé (par exemple dopage de type p). Cette zone dopée, couramment appelée émetteur, est généralement formée depuis la face avant du substrat, correspondant par principe à la face du substrat destinée à recevoir le rayonnement solaire. Cependant, dans certains cas, elle peut aussi être formée depuis la face arrière du substrat, c'est-à-dire généralement la face opposée à celle recevant le rayonnement solaire. Le rendement de conversion des cellules photovoltaïques à homojonction est en général limité par des pertes au niveau des faces avant et/ou arrière du substrat par recombinaison. II est connu de minimiser ces recombinaisons de surface en intégrant une couche de passivation en matériau diélectrique, destinée à réduire les états d'interface ou à créer un effet de champ favorable pour repousser les porteurs de charge vers la jonction, lieu où ils doivent être collectés. Différents diélectriques sont couramment utilisés dans le domaine des cellules photovoltaïques à homojonction. A homojunction photovoltaic cell comprises a junction formed in the same semiconductor material and for directly converting the received photons into an electrical signal. The homojunction is, in particular, formed in a crystalline silicon substrate comprising two regions having opposite doping types (n and p). More particularly, this can be obtained from a silicon substrate having a given type of doping (for example n-type doping) and in which a doped zone is formed according to a type of opposite doping (for example doping of type p). This doped zone, commonly called emitter, is generally formed from the front face of the substrate, corresponding in principle to the face of the substrate for receiving solar radiation. However, in some cases, it may also be formed from the rear face of the substrate, that is to say generally the face opposite to that receiving solar radiation. The conversion efficiency of the homojunction photovoltaic cells is generally limited by losses at the front and / or rear faces of the substrate by recombination. It is known to minimize these surface recombinations by integrating a passivation layer of dielectric material, intended to reduce the interface states or to create a favorable field effect to repel the charge carriers to the junction, where they must be collected. Different dielectrics are commonly used in the field of homojunction photovoltaic cells.
À titre d'exemple, Jianhua Zhao et al. dans l'article « 24.7% efficient PERL silicon solar celles and other high efficiency solar cell and module research at the university of New South Wales » (ISES Solar World Congress, Jérusalem, Israël, July, 1999.) mentionnent la présence d'une couche en oxyde de silicium d'une épaisseur de 20nm dans une cellule photovoltaïque à homojonction, obtenue par oxydation thermique dans un milieu de 1 ,1 ,1 trichloroéthane (TCA). Une telle couche en oxyde de silicium est amorphe. De même, le document GB 1 125 927 décrit la réalisation d'une couche de protection en oxyde thermique de silicium sur un substrat en matériau semiconducteur pour l'élaboration d'une cellule photovoltaïque. La formation de l'oxyde est réalisée à des températures comprises entre 600°C et 1000°C en présence d'eau et d'un précurseur de silicium. For example, Jianhua Zhao et al. in the article "24.7% efficient PERL silicon solar and other high efficiency solar cell and module research at the University of New South Wales" (ISES Solar World Congress, Jerusalem, Israel, July, 1999.) mention the presence of a silicon oxide layer with a thickness of 20 nm in a homojunction photovoltaic cell, obtained by thermal oxidation in a medium of 1, 1, 1 trichloroethane (TCA). Such a layer of silicon oxide is amorphous. Similarly, document GB 1 125 927 describes the production of a protective layer of silicon thermal oxide on a semiconductor material substrate for the production of a photovoltaic cell. The formation of the oxide is carried out at temperatures of between 600 ° C. and 1000 ° C. in the presence of water and a silicon precursor.
Le problème de l'oxyde thermique S1O2 est que sa réalisation reste chère. Ceci n'est donc pas compatible avec un procédé de réalisation de cellules photovoltaïques industriel bas coût. Par ailleurs, la passivation des surfaces n'est pas optimale. Objet de l'invention The problem of thermal oxide S1O2 is that its realization remains expensive. This is therefore not compatible with a process for producing low cost industrial photovoltaic cells. In addition, the passivation of the surfaces is not optimal. Object of the invention
L'invention a pour but de proposer un procédé d'élaboration d'une cellule photovoltaïque à homojonction présentant une bonne passivation de surface, tout en étant peu coûteuse. The object of the invention is to propose a process for producing a homojunction photovoltaic cell having good surface passivation, while being inexpensive.
On tend vers cet objet par les revendications annexées. This object is approached by the appended claims.
Description sommaire des dessins Brief description of the drawings
D'autres avantages et caractéristiques ressortiront plus clairement de la description qui va suivre de modes particuliers de réalisation de l'invention donnés à titre d'exemples non limitatifs et représentés aux dessins annexés, dans lesquels : Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention given by way of non-limiting example and represented in the accompanying drawings, in which:
- la figure 1 représente, schématiquement et en coupe, un mode de réalisation particulier d'une cellule photovoltaïque à homojonction selon l'invention.  - Figure 1 shows schematically and in section, a particular embodiment of a homojunction photovoltaic cell according to the invention.
- les figures 2 et 3 représentent, schématiquement et en coupe, des première et seconde variantes de réalisation de la cellule photovoltaïque selon la figure 1.  - Figures 2 and 3 show, schematically and in section, first and second embodiments of the photovoltaic cell according to Figure 1.
Description de modes particuliers de réalisation Selon un exemple particulier de réalisation illustré sur la figure 1 , une cellule photovoltaïque à homojonction comporte un substrat 1 en silicium cristallin. Celui-ci comporte en particulier : DESCRIPTION OF PARTICULAR EMBODIMENTS According to a particular exemplary embodiment illustrated in FIG. 1, a homojunction photovoltaic cell comprises a substrate 1 made of crystalline silicon. This includes in particular:
- une première région principale 2 présentant un type de dopage donné et a first main region 2 having a given type of doping and
- une seconde région principale 3, surmontant la première région principale 2 et présentant un type de dopage opposé à celui de la première région principale 2. Les première et seconde régions principales 2 et 3 du substrat 1 , avec leurs types de dopage opposés, forment, alors, la jonction de la cellule photovoltaïque. De plus, comme illustré sur la figure 1 , la seconde région principale 3, également appelée émetteur de la cellule photovoltaïque à homojonction, peut être, avantageusement, formée dans la partie supérieure du substrat 1 , en face avant 1a du substrat 1. La face avant 1a du substrat 1 formée dans la seconde région principale 3 est, sur la figure 1 , texturée (ou structurée) afin d'augmenter le confinement optique de la cellule. De plus, la texturation peut être réalisée, de manière classique dans le domaine des cellules photovoltaïques, sous la forme de pyramides. Alternativement, la face avant 1a du substrat 1 pourrait aussi être une surface polie chimiquement, par exemple selon des techniques de préparation de surface classiques dans le domaine photovoltaïque, telles que la gravure dans un bain chimique, par exemple, à base de KOH concentré. De la même manière, la face arrière 1 b du substrat 1 peut aussi être une surface texturée, par exemple sous forme de pyramides, ou bien être une surface polie. Dans le cas d'un polissage chimique de la face arrière 1b, celui-ci peut être réalisé par gravure dans un bain comprenant d'une solution comprenant HF, HNO3 et H2O2, dans des proportions 1 :3 :3. a second main region 3, surmounting the first main region 2 and having a doping type opposite to that of the first main region 2. The first and second main regions 2 and 3 of the substrate 1, with their opposite doping types, form, then, the junction of the photovoltaic cell. In addition, as illustrated in FIG. 1, the second main region 3, also called emitter of the homojunction photovoltaic cell, may advantageously be formed in the upper part of the substrate 1, on the front face 1a of the substrate 1. The face before 1a of the substrate 1 formed in the second main region 3 is, in Figure 1, textured (or structured) to increase the optical confinement of the cell. In addition, the texturing can be performed, conventionally in the field of photovoltaic cells, in the form of pyramids. Alternatively, the front face 1a of the substrate 1 could also be a chemically polished surface, for example according to conventional surface preparation techniques in the photovoltaic field, such as etching in a chemical bath, for example, based on concentrated KOH. In the same way, the rear face 1b of the substrate 1 can also be a textured surface, for example in the form of pyramids, or be a polished surface. In the case of a chemical polishing of the rear face 1b, it can be achieved by etching in a bath comprising a solution comprising HF, HNO 3 and H 2 O 2, in proportions 1: 3: 3.
Dans un mode avantageux de réalisation et tel qu'illustré sur la figure 1 , le substrat 1 peut également comporter, en face arrière 1b du substrat 1 , une troisième région 4 présentant un type de dopage permettant la formation d'un champ à l'interface arrière, également connu sous l'acronyme anglo- saxon BSF (« Back Surface Field »). Ainsi, sur la figure 1 , la troisième région 4 est en contact direct avec la première région principale 2. Elle présente, avantageusement, un dopage de type identique à celui de la première région principale 2. In an advantageous embodiment and as illustrated in FIG. 1, the substrate 1 may also comprise, on the rear face 1b of the substrate 1, a third region 4 exhibiting a type of doping enabling the formation of a field on the substrate. rear interface, also known by the acronym BSF ("Back Surface Field"). Thus, in FIG. 1, the third region 4 is in direct contact with the first main region 2. It presents, advantageously, doping of the same type as that of the first main region 2.
À titre d'exemple, le substrat 1 peut être un substrat en silicium cristallin comprenant une première région principale 2 dopée de type n. Dans ce cas, la seconde région 3 ou émetteur du substrat 1 présente, alors, un dopage de type opposé, p ou p+. La seconde région 3 est, par exemple, obtenue par une opération de diffusion de bore dans le substrat 1 , depuis la face avant 1a du substrat 1. Une telle opération permet d'obtenir, localement et en surface, un dopage de type p+. De même, une opération de diffusion de phosphore, depuis la face arrière 1b du substrat 1 , peut être, avantageusement, réalisée pour former la troisième région 4 (ou BSF) du substrat 1 , avec un dopage n+. For example, the substrate 1 may be a crystalline silicon substrate comprising a first n-doped main region 2. In this case, the second region 3 or emitter of the substrate 1 has, then, a doping of the opposite type, p or p +. The second region 3 is, for example, obtained by a boron diffusion operation in the substrate 1, from the front face 1a of the substrate 1. Such an operation makes it possible to obtain, locally and on the surface, a p + type doping. Similarly, a phosphorus diffusion operation, from the rear face 1b of the substrate 1, can advantageously be carried out to form the third region 4 (or BSF) of the substrate 1, with n + doping.
Par ailleurs, la cellule photovoltaïque comporte également au moins un film mince en oxyde cristallin de silicium 5, disposé directement sur une des faces avant ou arrière du substrat. Ce film mince en oxyde cristallin de silicium 5 est destiné à permettre la passivation de ladite face du substrat. Furthermore, the photovoltaic cell also comprises at least one thin film of crystalline silicon oxide 5, arranged directly on one of the front or rear faces of the substrate. This crystalline silicon oxide thin film 5 is intended to allow the passivation of said substrate face.
Sur la figure 1 , le film mince en oxyde cristallin de silicium 5 est disposé directement sur la face avant 1a du substrat 1. Il est, ainsi, en contact direct avec la seconde région principale 3 du substrat. Ainsi, dans l'exemple mentionné ci-dessus, c'est-à-dire dans le cas d'un émetteur (ou seconde région principale 3) dopée p+ par diffusion de bore dans du silicium cristallin dopé n, le film mince en oxyde cristallin de silicium 5 permet de passiver l'émetteur en silicium dopé par du bore. In FIG. 1, the crystalline silicon oxide thin film 5 is disposed directly on the front face 1a of the substrate 1. It is thus in direct contact with the second main region 3 of the substrate. Thus, in the example mentioned above, that is to say in the case of a transmitter (or second main region 3) p + doped by diffusion of boron in n-doped crystalline silicon, the oxide thin film Silicon crystalline 5 makes it possible to passivate the emitter in silicon doped with boron.
Le film mince 5 est en oxyde cristallin de silicium, c'est-à-dire un oxyde sous forme cristalline. En particulier, il est supposé que la forme cristalline de l'oxyde de silicium pourrait être, dans certains cas, la forme tridymite pour un substrat en silicium ayant un plan cristallographique (100). Le film mince en oxyde cristallin de silicium 5 a, avantageusement, une épaisseur supérieure ou égale à 2 nanomètres et inférieure ou égale à 20 nanomètres et, de préférence une épaisseur supérieure ou égale à 5 nanomètres et inférieure ou égale à 10 nanomètres. À titre d'exemple, le film mince en oxyde cristallin de silicium 5 peut avoir une épaisseur de 8 nm. The thin film 5 is crystalline silicon oxide, that is to say an oxide in crystalline form. In particular, it is assumed that the crystalline form of the silicon oxide could be, in some cases, the tridymite form for a silicon substrate having a crystallographic plane (100). The silicon crystalline oxide thin film 5 advantageously has a thickness greater than or equal to 2 nanometers and less than or equal to 20 nanometers and, preferably, a thickness greater than or equal to 5 nanometers and less than or equal to 10 nanometers. For example, the crystalline silicon oxide thin film 5 may have a thickness of 8 nm.
Un tel film mince 5 est, plus particulièrement, un film mince obtenu en oxydant le silicium d'une partie superficielle du substrat 1. Par partie superficielle du substrat 1 , on entend une zone du substrat 1 s'étendant depuis une surface libre du substrat 1 et notamment depuis une des faces avant 1a ou arrière 1b du substrat 1 , vers l'intérieur de celui-ci, sur une très faible épaisseur (avantageusement inférieure à 20nm). Such a thin film 5 is, more particularly, a thin film obtained by oxidizing the silicon of a surface portion of the substrate 1. By the superficial portion of the substrate 1 is meant an area of the substrate 1 extending from a free surface of the substrate 1 and in particular from one of the front faces 1a or rear 1b of the substrate 1, towards the inside thereof, over a very small thickness (advantageously less than 20 nm).
Avantageusement, l'oxydation permettant la formation du film mince 5 est une oxydation superficielle radicalaire, c'est-à-dire une oxydation réalisée au moyen de radicaux (ou radicaux libres). De tels radicaux sont en particulier des radicaux oxygénés, par exemple obtenus à partir d'oxygène, d'ozone et/ou d'eau. Les radicaux ainsi obtenus oxydent, alors, le silicium sur une partie superficielle du substrat 1. Advantageously, the oxidation allowing the formation of the thin film 5 is a radical surface oxidation, that is to say an oxidation carried out by means of radicals (or free radicals). Such radicals are in particular oxygen radicals, for example obtained from oxygen, ozone and / or water. The radicals thus obtained oxidize, then, the silicon on a superficial part of the substrate 1.
De plus, l'oxyde de silicium ainsi obtenu pendant l'oxydation radicalaire est au moins en partie sous une forme cristalline. Plus particulièrement, l'oxydation superficielle radicalaire du substrat en silicium est, avantageusement, contrôlée pour permettre la formation d'un film mince en oxyde de silicium sous une forme cristalline en contact direct avec une surface du substrat en silicium. L'oxydation superficielle radicalaire du substrat peut cependant, dans certains cas, entraîner la formation supplémentaire, sur l'oxyde cristallin de silicium, d'oxyde de silicium sous une forme amorphe. Préférentiellement, le film mince en oxyde cristallin de silicium et l'éventuelle couche en oxyde amorphe de silicium sont ainsi formés lors d'une unique étape consistant en une oxydation superficielle radicalaire d'une surface du substrat. Cependant l'oxyde cristallin de silicium formant le film mince 5 reste interposé entre le substrat 1 et l'oxyde amorphe de silicium. De plus, l'oxyde de silicium amorphe, avantageusement formé pendant l'oxydation superficielle radicalaire peut, éventuellement, être retiré par décapage, lors d'une étape spécifique suivant l'oxydation superficielle radicalaire et, plus particulièrement, avant la formation d'une éventuelle couche anti-reflet. In addition, the silicon oxide thus obtained during the radical oxidation is at least partly in a crystalline form. More particularly, the radical surface oxidation of the silicon substrate is advantageously controlled to allow the formation of a thin film of silicon oxide in a crystalline form in direct contact with a surface of the silicon substrate. Radical surface oxidation of the substrate can however, in some cases, lead to the additional formation on the crystalline silicon oxide of silicon oxide in amorphous form. Preferably, the crystalline silicon oxide thin film and the optional layer of amorphous silicon oxide are thus formed in a single step consisting of a radical surface oxidation of a surface of the substrate. However, the crystalline silicon oxide forming the thin film 5 remains interposed between the substrate 1 and the amorphous silicon oxide. In addition, the amorphous silicon oxide, advantageously formed during the radical surface oxidation, may optionally be removed by pickling, during a specific step following the radical surface oxidation and, more particularly, before the formation of a possible anti-reflection layer.
L'oxydation est, avantageusement, assistée à l'aide d'un plasma ou bien par application de rayonnements ultraviolets sur la surface du substrat à oxyder. Le traitement par plasma ou par rayonnements ultraviolets facilite, en particulier, la formation des radicaux libres utilisés pour oxyder le silicium du substrat 1. Ils sont, plus particulièrement, des radicaux de type Ο', O2 ' et/ou OH', selon le type de traitement et sont en particulier obtenus à partir d'oxygène et/ou d'ozone et/ou d'eau. The oxidation is advantageously assisted by means of a plasma or by the application of ultraviolet radiation to the surface of the substrate to be oxidized. The plasma or ultraviolet radiation treatment facilitates, in particular, the formation of free radicals used to oxidize the silicon of the substrate 1. They are, more particularly, de ' , O 2 ' and / or OH ' type radicals, according to the type of treatment and are in particular obtained from oxygen and / or ozone and / or water.
Selon un mode particulier de réalisation, l'oxydation de la partie superficielle du substrat 1 peut être réalisée à partir d'oxygène et de rayonnements ultraviolets ayant une gamme de longueurs d'onde comprise entre 160nm et 400nm. Les longueurs d'onde des rayonnements ultraviolets utilisés sont, par exemple, d'environ 185nm et d'environ 254nm. Dans ce mode particulier de réalisation, l'oxygène, sous l'action des rayonnements ultraviolets, se dissocie en radicaux libres O' et en ozone. Les radicaux libres peuvent oxyder la surface du silicium. De plus, la température pendant l'opération d'oxydation peut être comprise entre la température ambiante et environ 900°C. En particulier, l'étape de réalisation du film mince d'oxyde cristallin de silicium est, avantageusement, réalisée à une température inférieure à 800°C. Préférentiellement, la température est comprise entre 20°C et 400°C, notamment lors d'une oxydation radicalaire à partir de rayonnements ultraviolets et d'ozone. Encore plus préférentiellement, la température pendant l'étape d'oxydation radicalaire est la température ambiante. Par température ambiante, on entend, en général, une température comprise entre 20°C et 50°C. According to one particular embodiment, the oxidation of the superficial portion of the substrate 1 can be carried out using oxygen and ultraviolet radiation having a wavelength range of between 160 nm and 400 nm. The wavelengths of ultraviolet radiation used are, for example, about 185 nm and about 254 nm. In this particular embodiment, the oxygen, under the action of ultraviolet radiation, dissociates into free radicals O ' and ozone. Free radicals can oxidize the silicon surface. In addition, the temperature during the oxidation operation may range from room temperature to about 900 ° C. In particular, the step of producing the crystalline silicon oxide thin film is advantageously carried out at a temperature below 800 ° C. Preferably, the temperature is between 20 ° C and 400 ° C, especially during a radical oxidation from ultraviolet radiation and ozone. Even more preferentially, the temperature during the oxidation step radical is the ambient temperature. By ambient temperature is meant, in general, a temperature between 20 ° C and 50 ° C.
En effet, en dessous de 800°C, les profils de diffusion de l'émetteur et du BSF ne sont pas redistribués. De plus, l'émetteur notamment lorsqu'il s'agit d'un émetteur dopé au bore ne subit pas de déplétion forte en surface, ce qui représente un avantage au niveau de la passivation de surface., Indeed, below 800 ° C, the diffusion profiles of the transmitter and the BSF are not redistributed. In addition, the transmitter especially when it is a boron doped transmitter does not undergo strong depletion on the surface, which represents an advantage in terms of surface passivation.
De plus, pendant l'étape d'oxydation radicalaire, la pression peut être comprise entre environ 10"4 et environ 105 Pa, et préférentiellement l'étape d'oxydation est réalisée à pression ambiante. Par pression ambiante, on entend une pression de l'ordre de 1atm, soit de 1013,25 hPa. In addition, during the radical oxidation step, the pressure may be between about 10 -4 and about 10 5 Pa, and preferably the oxidation step is carried out at ambient pressure. of the order of 1atm, or 1013.25 hPa.
Ainsi, de manière encore plus avantageuse, la température et la pression de l'opération de formation du film mince en oxyde cristallin de silicium 5 sont respectivement la température ambiante et la pression ambiante. Par ailleurs, la cellule photovoltaïque peut comporter une ou plusieurs couches anti-reflet. Il peut s'agir d'une couche anti-reflet en SiN, déposée par dépôt chimique en phase vapeur assisté par plasma (PECVD), au niveau de la face avant 1a et/ou de la face arrière 1b du substrat 1 pour une action antireflet et de passivation accentuée des surfaces. Lorsque la couche anti-reflet est déposée au niveau de la face avant 1a du substrat, celle-ci a été préalablement munie du film mince en oxyde cristallin de silicium 5. Une telle couche anti-reflet a typiquement une épaisseur comprise entre 60nm et 80nm. La figure 2 illustre un mode de réalisation d'une cellule photovoltaïque comprenant, en plus des éléments représentés sur la figure 1 , une couche anti-reflet 6 disposée directement sur le film mince en oxyde cristallin de silicium 5 et une couche anti-reflet 7 disposée directement sur la face arrière 1b du substrat 1.  Thus, even more advantageously, the temperature and the pressure of the crystalline silicon oxide thin film forming operation are respectively room temperature and ambient pressure. Furthermore, the photovoltaic cell may comprise one or more anti-reflection layers. It may be a SiN layer, deposited by plasma-assisted chemical vapor deposition (PECVD), at the front face 1a and / or the rear face 1b of the substrate 1 for an action antireflection and accentuated passivation of surfaces. When the antireflection layer is deposited at the front face 1a of the substrate, it has been previously provided with the thin film of crystalline silicon oxide 5. Such an antireflection layer typically has a thickness between 60nm and 80nm . FIG. 2 illustrates an embodiment of a photovoltaic cell comprising, in addition to the elements represented in FIG. 1, an anti-reflection layer 6 disposed directly on the crystalline silicon oxide thin film 5 and an anti-reflection layer 7 arranged directly on the rear face 1b of the substrate 1.
Enfin, de manière classique, des contacts sont, plus particulièrement, réalisés sous forme de grille sur les deux faces avant et arrière du substrat pour collecter le courant photogénéré. Ces contacts peuvent être réalisés par sérigraphie, par électrodéposition, par évaporation, ...Si on utilise une sérigraphie d'une pâte adaptée, un recuit infrarouge permet de perforer les couches anti-reflet pour atteindre la jonction. La figure 3 illustre, ainsi, un mode de réalisation d'une cellule photovoltaïque, comprenant en plus des éléments représentés sur la figure 2, de tels contacts 8. Finally, in a conventional manner, contacts are more particularly made in the form of a grid on both front and rear faces of the substrate to collect the photogenerated current. These contacts can be made by screen printing, by electrodeposition, by evaporation, ... If we use a Screen printing of a suitable paste, an infrared annealing allows to perforate the anti-reflection layers to reach the junction. FIG. 3 illustrates, thus, an embodiment of a photovoltaic cell, comprising in addition to the elements represented in FIG. 2, such contacts 8.
Le film mince en oxyde cristallin de silicium, est en contact direct sur une des deux faces du substrat, et plus particulièrement sur la totalité de ladite face. Préférentiellement, après la formation des contacts, le film en oxyde cristallin de silicium de la cellule photovoltaïque, est toujours en contact direct sur une des deux faces du substrat, et plus particulièrement sur la totalité de ladite face, c'est-à-dire que le film mince en oxyde cristallin de silicium, servant de couche de passivation, n'est, par exemple, pas gravé lors de la formation des contacts. The crystalline silicon oxide thin film is in direct contact on one of the two faces of the substrate, and more particularly on the whole of said face. Preferably, after the formation of the contacts, the crystalline silicon oxide film of the photovoltaic cell is always in direct contact on one of the two faces of the substrate, and more particularly on the whole of said face, that is to say that the silicon crystalline oxide thin film serving as a passivation layer is, for example, not etched during the formation of the contacts.
Les exemples ci-dessus illustrent la réalisation d'un film mince en oxyde cristallin de silicium sur la face avant d'un substrat en silicium cristallin d'une cellule photovoltaïque à homojonction. Cependant, le film mince en oxyde cristallin de silicium ou bien un film mince en oxyde cristallin de silicium additionnel peut aussi être disposé directement sur la face arrière du substrat. À titre d'exemple, le substrat peut être un substrat en silicium cristallin de type p, dans lequel est formée une région dopée en face avant 1 formant un émetteur dopé n+ (par exemple par diffusion de phosphore depuis la face avant). Le substrat peut aussi comporter en face arrière une région dopée p+ (BSF) ou bien une région non dopée. Dans ce cas, le film mince d'oxyde cristallin de silicium est formé au niveau de la face arrière pour favoriser la passivation de surface. Des couches anti-reflet en SiN peuvent ensuite être déposées en face avant et/ou en face arrière du substrat et les contacts sont réalisés sous forme de grille également. The examples above illustrate the production of a silicon crystalline oxide thin film on the front face of a crystalline silicon substrate of a homojunction photovoltaic cell. However, the silicon crystalline oxide thin film or an additional silicon crystalline oxide thin film may also be disposed directly on the back side of the substrate. By way of example, the substrate may be a p-type crystalline silicon substrate, in which is formed a doped region on the front face 1 forming an n + doped emitter (for example by phosphor diffusion from the front face). The substrate may also comprise on the rear face a p + doped region (BSF) or an undoped region. In this case, the silicon crystalline oxide thin film is formed at the back side to promote surface passivation. SiN anti-reflection layers can then be deposited on the front face and / or rear face of the substrate and the contacts are also in grid form.
De la même manière, bien que la figure 3 illustre un cas où la cellule photovoltaïque comporte une couche anti-reflet pour chacune des faces avant 1a et arrière 1b du substrat 1 , les faces avant et arrière d'une cellule photovoltaïque selon l'invention peuvent être recouvertes ou non d'une couche anti-reflet. Enfin, la réalisation d'un film mince en oxyde cristallin de silicium peut être appliquée à tout type d'architecture de cellule photovoltaïque à homojonction. Elle peut, notamment s'appliquer, en plus de la structure standard décrite ci-dessus, aux cellules photovoltaïques bifaciales (avec éclairement des deux côtés du substrat), aux cellules à contacts interdigités (pour lesquelles l'émetteur et le BSF sont réalisés sur la même face de façon interdigitée), aux cellules à jonction face arrière, aux cellules à contacts face arrières (MWT pour « Metallisation warp through » ou EWT pour « emitter warp through »). In the same way, although FIG. 3 illustrates a case where the photovoltaic cell comprises an anti-reflection layer for each of the faces before 1a and rear 1b of the substrate 1, the front and rear faces of a photovoltaic cell according to the invention may or may not be covered with an anti-reflection layer. Finally, the production of a silicon crystalline oxide thin film can be applied to any type of homojunction photovoltaic cell architecture. It can, in particular, be applied, in addition to the standard structure described above, to bifacial photovoltaic cells (with illumination on both sides of the substrate), to interdigitated contact cells (for which the emitter and the BSF are made on the same face interdigitatively), backside junction cells, back-side contact (MWT) cells (EWT for "emitter warp through").

Claims

Revendications claims
1. Procédé de réalisation d'une cellule photovoltaïque à homojonction comprenant : A method for producing a homojunction photovoltaic cell comprising:
- un substrat (1 ) en silicium cristallin muni de deux faces, respectivement avant (1 a) et arrière (1 b), a substrate (1) of crystalline silicon provided with two faces, respectively before (1 a) and behind (1 b),
- deux régions principales (2, 3) présentant des types de dopage opposés, two main regions (2, 3) having opposite types of doping,
- un film mince en oxyde cristallin de silicium (5) disposé directement sur une des deux faces (1a, 1 b) du substrat (1), a thin film of crystalline silicon oxide (5) disposed directly on one of the two faces (1a, 1b) of the substrate (1),
caractérisé en ce que le film mince en oxyde cristallin de silicium (5) est réalisé par une oxydation superficielle radicalaire d'une surface du substratcharacterized in that the crystalline silicon oxide thin film (5) is produced by a radical surface oxidation of a surface of the substrate
(1). (1).
2. Procédé selon la revendication 1 , caractérisé en ce que l'oxydation superficielle radicalaire est réalisée au moyen de radicaux oxygénés obtenus à partir d'oxygène et/ou d'ozone et/ou d'eau. 2. Method according to claim 1, characterized in that the radical surface oxidation is carried out by means of oxygen radicals obtained from oxygen and / or ozone and / or water.
3. Procédé selon la revendication 2, caractérisé en ce que l'oxydation superficielle d'une surface du substrat (1) est assistée par application de rayonnements ultraviolets sur ladite surface. 3. Method according to claim 2, characterized in that the surface oxidation of a surface of the substrate (1) is assisted by application of ultraviolet radiation on said surface.
4. Procédé selon la revendication 3, caractérisé en ce que les radicaux oxygénés étant obtenus au moins à partir d'oxygène, les rayonnements ultraviolets ont une gamme de longueurs d'onde comprise entre 160 nm et 400 nm. 4. Method according to claim 3, characterized in that the oxygen radicals being obtained at least from oxygen, the ultraviolet radiation has a wavelength range of between 160 nm and 400 nm.
5. Procédé selon l'une des revendications 1 et 2, caractérisé en ce que l'oxydation superficielle d'une surface du substrat (1) est assistée par plasma. 5. Method according to one of claims 1 and 2, characterized in that the surface oxidation of a surface of the substrate (1) is assisted by plasma.
6. Procédé selon l'une des revendications 1 à 5, caractérisé en ce que l'oxydation superficielle d'une surface du substrat (1) est réalisée à une température inférieure à 800°C. 6. Method according to one of claims 1 to 5, characterized in that the surface oxidation of a surface of the substrate (1) is carried out at a temperature below 800 ° C.
7. Procédé selon la revendication 6, caractérisé en ce que l'oxydation superficielle d'une surface du substrat (1) est réalisée à une température comprise entre 20°C et 400°C. 7. Method according to claim 6, characterized in that the surface oxidation of a surface of the substrate (1) is carried out at a temperature between 20 ° C and 400 ° C.
8. Procédé selon l'une des revendications 1 à 7, caractérisé en ce que l'oxydation superficielle d'une surface du substrat (1) est réalisée à température ambiante et pression ambiante. 8. Method according to one of claims 1 to 7, characterized in that the surface oxidation of a surface of the substrate (1) is carried out at room temperature and ambient pressure.
9. Procédé selon l'une quelconque des revendications 1 à 8, caractérisé en ce que l'oxydation superficielle radicalaire d'une surface du substrat (1) est suivie d'une étape de décapage pour retirer une partie d'oxyde de silicium formée pendant l'oxydation superficielle radicalaire, sous forme amorphe, sur la surface du film mince (5). 9. Method according to any one of claims 1 to 8, characterized in that the radical surface oxidation of a surface of the substrate (1) is followed by a stripping step to remove a portion of formed silicon oxide during the free radical surface oxidation, in amorphous form, on the surface of the thin film (5).
10. Procédé selon l'une quelconque des revendications 1 à 9, caractérisé en ce que l'oxydation superficielle radicalaire d'une surface du substrat (1) est suivie d'une étape de formation d'une couche anti-reflet (6, 7). 10. Process according to any one of claims 1 to 9, characterized in that the radical surface oxidation of a surface of the substrate (1) is followed by a step of forming an anti-reflection layer (6, 7).
11. Procédé selon l'une quelconque des revendications 1 à 10, caractérisé en ce que le film mince en oxyde cristallin de silicium (5) a une épaisseur supérieure ou égale à 2 nanomètres et inférieure ou égale à 20 nanomètres. 11. Method according to any one of claims 1 to 10, characterized in that the thin film of crystalline silicon oxide (5) has a thickness greater than or equal to 2 nanometers and less than or equal to 20 nanometers.
12. Procédé selon la revendication 11 , caractérisé en ce que le film mince en oxyde cristallin de silicium (5) a une épaisseur supérieure ou égale à 5 nanomètres et inférieure ou égale à 10 nanomètres. 12. The method of claim 11, characterized in that the thin film crystalline silicon oxide (5) has a thickness greater than or equal to 5 nanometers and less than or equal to 10 nanometers.
13. Procédé selon l'une quelconque des revendications 1 à 12, caractérisé en ce que le film mince en oxyde cristallin de silicium (5) est disposé directement sur la face avant (1a) du substrat (1), ladite face avant (1a) constituant l'interface entre le film mince en oxyde cristallin de silicium (5) et une des deux régions principales (3) présentant des types de dopage opposés. Process according to one of Claims 1 to 12, characterized in that the crystalline silicon oxide thin film (5) is arranged directly on the front face (1a) of the substrate (1), said front face (1a) constituting the interface between the silicon crystalline oxide thin film (5) and one of the two main regions (3) having doping types opposed.
14. Procédé selon l'une quelconque des revendications 1 à 13, caractérisé en ce qu'une couche en oxyde amorphe de silicium est disposée directement sur le film mince en oxyde cristallin de silicium (5). 14. Method according to any one of claims 1 to 13, characterized in that a layer of amorphous silicon oxide is disposed directly on the thin film crystalline silicon oxide (5).
15. Procédé selon l'une quelconque des revendications 1 à 14, caractérisé en ce que le substrat cristallin (1) comporte, en face arrière (1 b), une région additionnelle (4) présentant un type de dopage permettant la formation d'un champ à l'interface arrière. 15. Method according to any one of claims 1 to 14, characterized in that the crystalline substrate (1) comprises, on the rear face (1 b), an additional region (4) having a doping type allowing the formation of a field at the rear interface.
16. Procédé selon l'une quelconque des revendications 1 à 15, caractérisé en ce qu'au moins une des deux faces (1a, 1b) du substrat (1) en silicium cristallin est texturée. 16. A method according to any one of claims 1 to 15, characterized in that at least one of the two faces (1a, 1b) of the substrate (1) of crystalline silicon is textured.
PCT/FR2012/000266 2011-07-05 2012-07-04 Method for producing a homojunction photovoltaic cell comprising a passivation thin film made from crystalline silicon oxide WO2013004923A1 (en)

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FR1102107A FR2977717A1 (en) 2011-07-05 2011-07-05 PHOTOVOLTAIC HOMOJUNCTION CELL COMPRISING A THIN SILICON CRYSTALLINE OXIDE PASSIVATING FILM AND METHOD OF MAKING SAME
FR11/02107 2011-07-05

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