Multisubband hot-electron transport in GaN-based quantum wells

A simple rigorous analytical theory of two-dimensional (2D) nonequilibrium electrons occupying an arbitrary number of subbands in a quantum well is developed. The electric-field dependence of electron mobility and the average kinetic energy for AlN/GaN quantum wells are presented. At temperatures below 200 K the electron mobility is controlled mainly by the acoustic phonon scattering and it is a nonmonotonous function of the electric field, which has a maximum. At room and higher temperatures the interaction with both acoustic and polar optical phonons determine the hot-electron mobility and it depends very weakly on the electric field. Both the mobility and average energy of 2D electrons are smaller than that for three-dimensional (3D) electrons in the bulk semiconductor. Our theory provides a self-consistent transition from the 2D to the 3D regime of electron transport with increasing electric field accompanied by the occupation of an increasingly large number of subbands by the electrons. (C) 1998 American Institute of Physics. [S0003-6951(98)03943-6].