We use the Monte Carlo technique to treat hot-electron energy dissipation on equilibrium phonons at a lattice temperature of 300 K in donor-doped wurtzite GaN subjected to an electric field. Two concurrent energy relaxation processes (fast and ultrafast) are resolved. The energy relaxation time of the ultrafast process is ∼25 fs; its dependence on the field and the doping is very weak (if any). In contrast, pair electron-electron collisions are found to enhance the fast energy dissipation considerably. In particular, at a field of 0.2 kV cm −1 , the relaxation time of the fast process decreases from 2.8 ps to 0.3 ps as the electron density increases from 4 × 10 15 cm −3 to 3 × 10 17 cm −3 . The time decreases as the electric field increases; values below 0.1 ps are reached at 10 16 cm −3 at fields exceeding 8 kV cm −1 .

Extrapolated experimental dependence of electron energy relaxation time is used to treat hotelectron sharing by the adjacent Al 0:15 Ga 0:85 N and GaN layers in Al 0:15 Ga 0:85 N/GaN. The results fit the available experimental data on microwave noise when hot-phonon effect on the energy relaxation time is taken into account. The relaxation time of the occupancy fluctuations of the shared states is estimated to be 6 ps at 80 K lattice temperature.

We study the effect of doping on hot-electron fluctuation phenomena in gallium arsenide (GaAs). We obtain the noise characteristics of pure and doped n-type GaAs channels at applied electric fields from Monte Carlo simulations of the kinetic processes in the framework of a realistic model of GaAs. We achieve a fit with the available experimental data, and we reveal the effects of inter-electron collisions and the degree of compensation of donors on microwave fluctuation characteristics at heated electric fields. We confirm the sensitivity of nonequilibrium noise phenomena to the presence of inter-electron collisions, though conserving energy and quasi-momentum in the system of electrons.