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The Monte Carlo simulation of hot-electron energy dissipation is carried out for a biased AlGaN / AlN / GaN channel. The conduction band profile and electron wave functions are calculated through self-consistent solution of Poisson and Schrödinger equations. Nonelastic scattering of electrons on acoustic phonons and nonequilibrium longitudinal optical ͑LO͒ phonons is included. The nonequilibrium LO phonons are treated in terms of hot-phonon lifetime. The dependence of electron temperature and dissipated power on the applied electric field is obtained from the Monte Carlo simulation. The experimental results on noise temperature and current as functions of electric field strength applied along the channel are presented, and the dependence of the supplied electric power on the inverse electron temperature is evaluated. The best agreement between the Monte Carlo results and the experimental data is obtained for the hot-phonon lifetime ph = 1 ps.

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Current–voltage characteristics of a nominally undoped AlGaN/GaN two-dimensional electron gas channel is measured at a room temperature, and electron drift velocity is deduced under assumption of uniform electric field and field-independent electron density. No velocity saturation is reached at fields up to 130 kV/cm, when the effect of Joule heating is minimized through application of nanosecond pulses of voltage. The estimated drift velocity is near 2×107 cm/s at 130 kV/cm. Monte Carlo simulation of the drift velocity is carried out with and without effects of channel self-heating for a many-subband model, with hot phonons and electron gas degeneracy taken into account.

Dependence of hot-electron noise temperature on supplied electric power is measured at room temperature for an AlGaN/AlN/GaN channel with a two-dimensional electron gas (1 × 10 13 cm −2 ). The results are interpreted in an electron-temperature approximation for a 5-subband model with electron-gas degeneracy taken into account. The fitting is obtained when non-equilibrium (hot) longitudinal optical (LO) phonons are taken into account. The estimated effective occupancy of the involved LO-phonon states exceeds the equilibrium one more than 30 times at 2000 K electron temperature.