Simulation of GaAs IMPATT diodes including energy and velocity transport equations

Simulations have been performed of GaAs hybrid double-drift IMPATT diodes at 60 and 94 GHz using a transport model which includes equations for the average per-carrier velocity and energy. These equations are obtained from the second and third velocity moments of the Boltzmann transport equations, respectively. The relaxation-time formulation is used to characterize the collision terms. Simulations were also carried out for the same structures using the standard drift-diffusion transport model. It was found that inclusion of the energy-velocity equations significantly modifies the predicted carrier transport behavior and results in somewhat better RF performance under large-signal conditions than that predicted by the drift-diffusion simulation.