Defect formation in SiGe/Si structures grown on GaAs by CVD techniques utilizing a Si:H template layer

Epitaxial SiGe layers and Si/SiGe modulated heterostructures were successfully grown on GaAs substrates by chemical vapor deposition (CVD) techniques utilizing an amorphous-Si:H buffer layer as a transition layer between SiGe and GaAs. Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) were used to investigate the structural quality of the SiGe layers on GaAs. It was shown that the amorphous transition layer of silicon resulted in an initial 2D epitaxial growth of SiGe films on GaAs. However, the SiGe films were found to be strained and threading dislocations were observed. Traps in SiGe films were identified to be mainly minority type at 0.15–0.20 eV, in addition to the two majority traps at 0.25 and 0.46 eV. The DC characteristics of SiGe Schottky diodes on GaAs substrates were also measured, and showed that the barrier height varied from 0.35 to 0.85 eV depending on the Ge concentration.