COMPARISON BETWEEN THE RELAXATION-TIME APPROXIMATION AND THE BOLTZMANN COLLISION OPERATOR FOR SIMULATION OF DISSIPATIVE ELECTRON-TRANSPORT IN RESONANT-TUNNELING DIODES

Carrier scattering in the Wigner formalism has been introduced for the simulation of dissipative electron transport in resonant tunnelling d iodes. Two approaches have been considered: the relaxation time approx imation and the Boltzmann collision operator. The relaxation time and transition rates have been evaluated and have been introduced in the d iscretized version of the Liouville equation to obtain the Wigner dist ribution function and the current density. Not only phonon scattering, but also ionized impurity scattering has been accounted for in both a pproaches. We have compared the two scattering models on the basis of the I-V characteristics which have been simulated under various temper ature and doping conditions. The results clearly reveal a lower curren t peak in the Boltzmann collision operator approach. Since the results of both approaches are divergent and since no clear computation advan tages are obtained from the relaxation time approximation, we prefer t he use of the more realistic Boltzmann collision operator for the simu lation of dissipative electron transport in resonant tunnelling diodes . Copyright (C) 1996 Elsevier Science Ltd