NEAR-SURFACE ELECTRONS AND ACOUSTIC PHONONS - ENERGY AND MOMENTUM RELAXATION

We study energy and momentum relaxation of a two-dimensional (2D) elec tron channel located at a finite distance l from a free crystal surfac e. The interaction with a complete set of bulklike, totally reflected, and Rayleigh acoustic phonon modes is taken into account, In most cas es of interest the relaxation rates have the same temperature dependen ce as for 2D or bulk electrons interacting with bulk phonons. Numerica l calculations demonstrate that the presence of a surface results in a pproximately a 10% modification of scattering rates in the high-temper ature region, In the opposite limit (Bloch-Gruneisen regime), the cont ribution of the surface phonons may dominate over that of bulklike mod es. Oscillations of the relaxation rates as a function of the distance l between the electron channel and the surface are also predicted. [S 0163-1829(97)01148-X].