Dynamics of hot-electron scattering in GaN heterostructures

A detailed comparison is made between the hot-electron rates for energy and momentum relaxation in electron-acoustic-phonon scattering and energy and momentum exchange rates in electron-electron scattering in a GaN heterostructure. In the case of piezoelectric scattering full account is taken of the anisotropy of the interaction and corresponding form factors have been calculated. The interaction with acoustic phonons is assumed to be statically screened. Dynamic screening of the electron-electron interaction is shown to give rise to resonances associated with plasmon-phonon coupled mode effects with overall dynamic rates rather insensitive to electron density at least for densities around $1\times {10}^{12}{\mathrm{cm}}^{-2}.$ At these densities electron-electron scattering easily dominates the energy and momentum distribution at energies below the optical-phonon energy and is comparable with the optical phonon contribution above the phonon energy. The condition for the formation of a drifted Maxwellian distribution is discussed.