Simulation of an Al xGa 1− xAs ballistic diode using multivalley nonparabolic hydrodynamic balance equations

Abstract

Nonparabolic multivalley hydrodynamic balance equations are presented as an extension of the hydrodynamic equations for nonparabolic single valley semiconductors and of the balance equations for homogeneous multivalley nonparabolic semiconductors. Its main features which differ from the conventional hydrodynamic equations lie in: (1) a nonparabolicity-related factor, the ensemble-averaged inverse-effective mass, associated with the field acceleration term in the momentum-balance equation; (2) the collisional terms, which are expressed by functions of particle transition, frictional acceleration and energy-loss rate, by which the variation of the conduction band structure and intervalley kinetics are automatically included. As an example, we apply this set of balance equations to a self-consistent numerical simulation of a ballistic diode made of Al x Ga 1− x As with a two-valley structure. The nonlinear electron transport characteristics, such as velocity overshoot and intervalley transfer, at several values of applied potential and composition are analyzed and discussed.