Nonequilibrium phonon effects on the transient high-field transport regime in InP.

We present a detailed investigation of the transient transport regime in InP at room temperature based on an original method to solve numerically the coupled hot-phonon--hot-carrier time-dependent Boltzmann equations for the case of a steplike high dc electric field pulse. The method enables a study of the perturbation of the phonon distribution function induced by hot carriers and the corresponding modifications of the carrier distribution function. The numerical accuracy of the method is far beyond other existing methods, and, as a consequence, the time behavior of the main transport parameters can be resolved in great detail. The presence of nonequilibrium phonons is found to be responsible for an overall increase in the time duration of the transient regime. Modifications in the time evolution of the main transport parameters are also observed; in particular, the carrier drift velocity exhibits a second overshoot for electric fields near the threshold value for negative differential mobility. The sensitivity of the results to the value of the phonon relaxation time is also discussed. \textcopyright{} 1996 The American Physical Society.