Large transconductance n+-Ge gate AlGaAs/GaAs MISFET with thin gate insulator

The effects of insulator layer thickness on an n+-Ge gate MISFET were studied. The transconductance increases with decreasing AlGaAs layer thickness from 60 down to 10 nm. From the variation of the intrinsic transconductance, the effective insulator layer thickness was found to be enlarged by about 9 nm. This is due to the finite width of two-dimensional electron gas (2-DEG). A large transconductance of 430 mS/ mm was obtained at room temperature for the 0.8-µm gate-length FET with 10-nm-thick AlGaAs. This large transconductance demonstrates the inherent potential of the n+-Ge gate MISFET for LSI application.