Abstract
The behavior of short-wave-length acoustic phonons in the vicinity of a quantum well in a GaAs/AlGaAs heterostructure has been investigated. Hot two-dimensional electrons in the well produce longitudinal optical phonons, which decay into almost monoenergetic short-wave-length longitudinal acoustic (LA) phonons. The latter undergo elastic scattering and down-conversion into transverse acoustic (TA) phonons. The distribution of the LA and TA phonons over frequency and distance to the well have been found by solving semi-analytically a system of two kinetic equations with nontrivial boundary conditions and nonlinear dispersion. The distribution functions have essentially non-temperature form even at substantial distance from the well.
Highlights
MOTIVATION AND OBJECTIVESThe charge carriers heating in the conducting channel of a semiconductor heterostructure device is mainly controlled by the phonon system feedback
These distribution functions are essentially determined by a complicated interplay of elastic scattering and anharmonic decay rates, both of which substantially depend on phonon energy
The key processes of down-conversion are controlled by anharmonicity of the lattice vibrations, the elastic scattering is mainly due to isotopic impurities
Summary
The charge carriers heating in the conducting channel of a semiconductor heterostructure device is mainly controlled by the phonon system feedback. The feedback effects, in their turn, are determined by spatial, energy, and modal distributions of the acoustic phonons transferring the excessive lattice energy. The energy dissipation from the device operation area is described by the thermoconductivity equations or in the modified framework of non-local heat transfer [1]. We show that this approach fails under high rate of phonon generation in the device operation channel. We obtain the spatial and energy distribution of the phonons in steady state, and demonstrate their drastically non-temperature form
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