Full band Monte Carlo simulation of zincblende GaN MESFET's including realistic impact ionization rates

In this paper, we present the first theoretical study of the breakdown prop erties of zincblende phase GaN MESFET devices. The calculations are made us ing a full band, ensemble Monte Carlo simulation that includes a numerical formulation of the impact ionization transition rates. The breakdown voltag e, transconductance and cutoff frequency are calculated for the GaN MESFET under two different conditions, with and without semiconductor-oxide interf ace states. Uniform surface depletion regions model the effect of the inter face states. It is found that the breakdown voltage of the zincblende GaN M ESFET is less dependent upon the surface depletion conditions than a corres ponding GaAs MESFET. It is also found that the drain current increases more gradually with increasing drain-source voltage at the onset of breakdown a nd that the breakdown voltage of the zincblende GaN MESFET is predicted to be several times larger than that of a comparable GaAs MESFET. The maximum current gain cutoff frequency of a 0.1 mu m gate length GaN MESFET is calcu lated to be 230 and 220 GHz, for the non-surface-depleted and the surface d epleted devices respectively.