Computer modeling of millimeter wave IMPATT diodes

A computer model of millimeter was Si IMPATT diodes was developed, which incorporates a more detailed description of charge transport than that given by the conventional drift and diffusion approximation. The new model is based on principles of conservation of energy and momentum, and provides a second order description of the time and space evolution of the carrier velocity distribution. The relevant transport equations are the first three velocity moments of the phase space transport equation. Terms accounting for the effects of collisions incorporate energy dependent relaxation times and ionization rates. These functions of energy were evaluated by using the requirements of consistency with experimental measurements of transport parameters. Finite difference approximations to the transport equations were developed, and problems of stability and accuracy of the approximations were analyzed and overcome.