Making complementary integrated p-MODFET and n-MODFET

Claim 1

An integrated circuit fabrication method for forming complementary field effect transistors on the same wafer substrate, comprising: epitaxially growing an intrinsic semiconductor buffer layer on a semiconductor substrate layer; epitaxially growing a semiconductor spacer layer on the buffer layer, said spacer layer being of different chemical composition and with a larger bandgap than said buffer layer; forming on said spacer layer an n-type doped semiconductor layer composed of the same material as said spacer layer; forming on said n-type doped layer a surface passivating n-type doped semiconductor cap layer composed of the same material as said buffer layer; implanting sufficient p-type ions into a selected portion of the n-type doped layer to transform said portion into a p-type layer; forming a pair of windows through the cap layer to expose portions of the n-type and p-type doped layers, respectively; forming a gap through the cap, semiconductor and the spacer layer and into the buffer layer to isolate the p-doped region from the n-doped region; and depositing respective source and drain contacts on the cap layer on opposite sides of each of said windows, and gate contacts on the underlying doped layers within said windows.