Silicium germanium heterodevices

Silicium germanium (SiGe) is a completely miscible alloy with a lattice mismatch to the Si substrate of up to 4.17%. Accommodation of lattice mismatch f causes elastic strain epsilon, and/or misfit dislocations and surface corrugations. Onset of misfit dislocation generation takes place above a critical thickness t(c) which is dependant on mismatch and growth temperature. Critical thicknesses are compared for equilibrium models (Matthews-Blakeslee, > 750 degrees C) with fit curves for 550 degrees C growth experiments (People-Bean). The most important factors for successful silicon based heterodevices are analyzed, and as attractive areas for future research are defined; heterobipolar transistors (HBT) for high frequency communication, complementary heterojunction field effect transistors (HFET) fdr digital logic, 1.3 mu m waveguide receivers for opto/microelectronics integration and self assembled quantum dot devices :For multifunctional long term applications. Treatment of surface corrugations, adatom behaviour, surfactant phenomena and surface passivation of devices will be an essential part of future device oriented research.