Threshold Voltage Behavior for WSi/Al_xGa_1-xAs/GaAs MIS-Like Heterostructure FET

WSi/Al x Ga 1- x As/GaAs MIS-like heterostructure FET (MIS-HFET) is compared with HFET fabricated using the same MBE apparatus. Threshold voltage ( V T ) variation through a wafer is much less for MIS-HFET (±0.05 V) than for the present HEMT (±0.15 V∼±0.4 V). In addition, threshold voltage shift as lowering the temperature from 300 K to 85 K is also much less for MIS-HFET (0.05 V) than for HMET (0.22 V). As it is simpler for MIS-HFET to obtain high V T uniformity and small V T dependence on temperature than for HEMT, MIS-HFET is believed to be attractive for LSI application.