ELECTRON-PHONON SCATTERING AND ANISOTROPY OF CONDUCTIVITY IN QUASI-2-DIMENSIONAL SYSTEMS

The inverse relaxation time tenser in quasi-two-dimensional systems is calculated for elastic electron scattering by both acoustic and optic al phonons. It is shown that in the general case the relaxation time i s anisotropic. Also, on the basis of the Boltzmann equation in the ani sotropic relaxation time approximation the electrical conductivity in these systems is calculated. It is found that anisotropy of the conduc tivity is defined not only by the anisotropy of effective mass and the relaxation time but also by the ratio of the Fermi level to the one-d imensional conduction band half-width. A comparison with available exp erimental data has been carried out. Qualitative agreement of theory w ith experiment was obtained.