A high threshold voltage uniformity MIS-like heterostructure FET using n+-Ge as a gate electrode

A new n+-Ge/ undoped-AlxGa1-xAs/ undoped-GaAs MISlike heterostructure FET (n+-Ge-HFET), using n+-Ge layer as a gate electrode material, is shown to have a high threshold voltage uniformity (\sigmaV_{TH} = 11mV) over a large sample area of a 2-in wafer quadrant. This is thought to come from the FET structure, for which the threshold voltage is principally determined by the difference in the electron affinities of Ge and GaAs. The high VTHuniformity, as well as the positive FET characteristics (g_{m} = 170mS/mm,V_{TH} = 0.25V), makes n+-Ge-HFET very attractive for LSI application.