Patent ID: 7259084

Claim:
A process for growing a GaAs epitaxial layer on Ge/SiGe/Si substrate comprising steps of: (1) providing a clean silicon wafer; (2) growing a first SiGe epitaxial layer with a certain thickness, wherein the layer comprises at least 70 wt. % of Ge; (3) performing in-situ high temperature annealing for the first layer; (4) growing a second and/or an optional third layers wherein the Ge content of the optional third layer is more than that of the second layer, and the Ge content of the second layer is more than that of the first layer, and during each of two growing periods, performing in-situ high temperature annealing for those layers; (5) growing a pure Ge film on the epitaxial layer from step (4); (6) finally, growing GaAs epitaxy on said Ge film.