Analysis of DC characteristics and small signal equivalent circuit parameters of GaAs metal-semiconductor field effect transistors with different gate lengths and different gate contours by two-dimensional device simulations

The gate length and gate contour of a GaAs metal-semiconductor field effect transistor (MESFET) device play important roles in determining the small signal circuit parameters and large signal breakdown voltage behavior. GaAs MESFETs with different gate lengths and gate contours were studied by the two-dimensional (2-D) semiconductor device simulations to investigate the dependence of small signal circuit parameters and breakdown voltage on gate length and gate contour. The results show that gate length affects small-signal circuit parameter C_gs while gate contour affects C_gd. The breakdown voltage has strong dependence on gate contour and little dependence on gate length.