A Semi-Analytical Interpretation of Transient Electron Transport in Gallium Nitride, Indium Nitride, and Aluminum Nitride

ABSTRACTThe energy dependent momentum and energy relaxation times, and the effective single valley energy dependent effective mass, are extracted from Monte Carlo simulations of gallium nitride, indium nitride, and aluminum nitride. A simple semi-analytical energy model, which uses these dependencies, is in good agreement with the results of transient Monte Carlo simulations. Both the Monte Carlo and the semi-analytical simulations show that the overshoot effects are most pronounced when the electric field abruptly changes from a value below a critical field to one above. This is attributed to the relatively large difference between the effective energy and momentum relaxation times for such a variation of electric field. Our calculations indicate that gallium nitride and indium nitride should have the most pronounced transient effects. A calculation of the transit times as a function of the gate length shows that an upper bound for the maximum expected cut-off frequencies are 260 GHz and 440 GHz for 0.2 μm gallium nitride and indium nitride field effect transistors, respectively.