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Accumulation of non‐equilibrium longitudinal optical (LO) phonons (termed hot phonons) is considered as a possible cause for limitation of hot‐electron drift velocity at high electric fields in a GaN biased channel with a two‐dimensional electron gas (2DEG). Equivalent hot‐phonon temperature and hot‐phonon lifetime are estimated from experimental results on hot‐electron noise at a microwave frequency. Dependence of the hot‐phonon parameters on electron density and channel composition is investigated, and frequency performance of high‐electron‐mobility transistors (HEMTs) is discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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.

A microwave noise technique has been used for experimental investigation, at room temperature, of power dissipation in the voltage-biased two-dimensional electron gas channel located in the GaN layer of a lattice-matched Al 0.82 In 0.18 N/AlN/GaN heterostructure. No saturation of the relaxation time is found in the investigated electron temperature range up to ∼2800 K: the hot-electron energy relaxation time decreases from ∼6 ps at near equilibrium to 75 ± 20 fs at ∼200 nW/electron. The electron drift velocity reaches ∼1.8 × 10 7 cm s −1 at 65 kV cm −1 electric field. The hot-phonon effect on power dissipation is discussed.

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