The bipolar transistor of the present invention includes a Si collector buried layer, a first base region made of a SiGeC layer having a high C content, a second base region made of a SiGeC layer having a low C content or a SiGe layer, and a Si cap layer 14 including an emitter region. The C content...http://www.google.fr/patents/US6759697?utm_source=gb-gplus-shareBrevet US6759697 - Heterojunction bipolar transistor
