Epitaxial growth of SiGe on Al2O3 using Si2H6 gas and Ge solid source molecular beam epitaxy

SiGe films were epitaxially grown on sapphire (0001), (011(2)over bar>) and gamma-Al2O3(111)/Si(111) using Si2H6 gas and Ge solid source molecular beam epitaxy (Si2H6-Ge MBE) for the first time. The orientation relationship between SiGe and Al2O3 was investigated, by reflection high-energy electron diffraction, as a function of the growth temperature. Epitaxial growth of SiGe films on Al2O3 was possible at low temperatures in comparison with the epitaxial growth of Si. From X-ray photoelectron spectroscopy, it is considered that the low-temperature growth of SiGe was achieved by the suppression of surface reaction by-products during the initial growth, because the continuous layer of SiGe was grown earlier due to short incubation times and a high growth rate. High nucleation densities and the high Ge contents of SiGe films at the heterointerface were observed and is considered to be due to the difference of the initial growth between Si2H6 gas and Ge atoms.