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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.

The microwave noise technique is used to estimate the hot-electron energy relaxation time in an AlGaN/GaN heterostructure containing a two-dimensional electron gas subjected to a strong electric field applied in the plane of electron confinement. Room-temperature data show that the energy relaxation time decreases monotonously from about 1 ps at 2 kV cm −1 to 0.4 ps at 10 kV cm −1 electric field. The estimated low-field value is 1.4 ps.

Ensemble Monte Carlo simulation of two-dimensional electron transport is carried out for an AlGaN/GaN heterostructure channel subjected to an electric field applied in the plane of electron confinement. The envelope wavefunctions for the confined electrons are calculated using a self-consistent Poisson-Schrödinger solver. The effects of electron-gas degeneracy and hot phonons on electron energy relaxation and drift velocity are investigated. The best fit between Monte Carlo simulation and experimental results is received with optical-phonon relaxation time τ ph = 1 ps. The results of simulation show that the degeneracy reduces the electron drift velocity while the hot phonons reduce the electron drift velocity and increase the electron energy relaxation time. Electron energy relaxation time approaches 0.3 ps at 10 kV cm −1 at room temperature.

Decay of nonequilibrium longitudinal optical ͑LO͒ phonons is investigated at room temperature in two-dimensional electron gas channels confined in nearly lattice-matched InAlN/AlN/GaN structures. A nonmonotonous dependence of the LO-phonon lifetime on the supplied electric power is reported for the first time and explained in terms of plasmon-LO-phonon resonance tuned by applied bias at a fixed sheet density ͑8 ϫ 10 12 cm −2 ͒. The shortest lifetime of 30Ϯ 15 fs is found at the power of 20Ϯ 10 nW/ electron.