Analysis of high electron mobility transistors based on a two-dimensional numerical model

A two-dimensional numerical model is employed to simulate the device performance of the high electron mobility transistor. A 1- µm gate device is analyzed using the equilibrium velocity-field characteristic of GaAs. The calculation reveals existence of electron accumulation in the GaAs layer under the drain side end of the gate electrode. A quasi-piecewise linear velocity-field characteristic is also employed to simulate the velocity overshoot effect. The cutoff frequency is found to be improved by about 50 percent owing to the velocity overshoot effect.