Piezoelectric electron-phonon interaction in impure semiconductors: Two-dimensional electrons versus composite fermions

We study the effects of piezoelectric coupling between two-dimensional electrons and bulk phonons in cases of both zero and strong perpendicular magnetic fields, the latter corresponding to even-denominator filling fractions. In contrast to the case of coupling via the deformation potential, the leading contributions due to impurity-renormalized electron-phonon vertices are not exactly canceled by processes of inelastic electron-impurity scattering. Electron energy relaxation time, diffusion correction to the conductivity, and the phonon emission rate by hot electrons are computed for realistic GaAs/AlxGa1-xAs heterostructures. [S0163-1829(97)07147-6].