SIMULATION OF AN ALXGA1-XAS BALLISTIC DIODE USING MULTIVALLEY NONPARABOLIC HYDRODYNAMIC BALANCE-EQUATIONS

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 mul tivalley nonparabolic semiconductors. Its main features which differ f rom the conventional hydrodynamic equations lie in: (1) a nonparabolic ity related factor, the ensemble-averaged inverse-effective mass, asso ciated with the held acceleration term in the momentum-balance equatio n; (2) the collisional terms, which are expressed by functions of part icle transition, frictional acceleration and energy-loss rate, by whic h the variation of the conduction band structure and intervalley kinet ics are automatically included. As an example, we apply this set of ba lance equations to a self-consistent numerical simulation of a ballist ic diode made of AlxGa1-xAs with a two-valley structure. The nonlinear electron transport characteristics, such as velocity overshoot and in tervalley transfer, at several values of applied potential and composi tion are analyzed and discussed. (C) 1997 Elsevier Science Ltd.