SiGe alloys and heterojunctions - extending the performance of Si devices

Advanced growth methods like molecular beam epitaxy and chemical vapour deposition allow the epitaxy of SiGe layers on Si substrates at rather low temperatures (typically 500°C–750°C). With Ge on Si, island growth commences which may be exploited for self-assembled nanostructures. The frequency limit of heterobipolar transistors with an SiGe base clearly exceeds 100 GHz. A variety of heterojunction field effect transistors, optoelectronic devices and novel device structures like the charge injection transistor demonstrate improved performance data.