A GaAs defect-free epitaxial layer was grown on Si via a Ge concentration graded SiGe on insulator for application in high channel-mobility metal-oxide-semiconductor field effect transistor. The SiGe on insulator layer, 42nm thick, serves as the compliant and intermediate buffer to reduce the lattice and thermal expansion mismatches between Si and GaAs. A modified 2-step Ge condensation technique achieved a surface Ge concentration in SiGe on insulator as high as 71%. It was also found that low-temperature migration enhanced epitaxy during the initial GaAs nucleation on the SiGe on insulator surface was critical to obtaining a device quality GaAs layer by epitaxial growth.

Integration of GaAs Epitaxial Layer to Si-Based Substrate Using Ge Condensation and Low-Temperature Migration Enhanced Epitaxy Techniques. H.J.Oh, K.J.Choi, W.Y.Loh, T.Htoo, S.J.Chua, B.J.Cho: Journal of Applied Physics, 2007, 102[5], 054306