ACOUSTIC-PHONON SCATTERING IN A RECTANGULAR QUANTUM-WIRE

The rates of electron scattering by acoustic phonons in a rectangular quantum wire embedded into another material are calculated in the fram ework of the Fermi golden rule. Both intrasubband and intersubband ele ctron scattering by acoustic phonons are considered. It has been shown that due to uncertainty of momentum conservation in quasi-one-dimensi onal systems the acoustic-phonon scattering becomes essentially inelas tic in contrast to that in bulk materials. The acoustic-phonon scatter ing rate in quantum wires increases with the decrease of cross section of the wire and is much greater than that in bulk materials. It is sh own that the correct treatment of inelasticity leads to a nonmonotonic dependence of the emission rate on electron energy and to the disappe arance of the divergency of the acoustic-phonon scattering rate at the bottom of each subband. Therefore, the scattering time averaged over the distribution function exceeds considerably that calculated using e lastic and quasielastic approaches where the scattering rate is diverg ent. We demonstrate that electron mobility at temperatures less than 1 00 K calculated within elastic or quasielastic approximations is great ly underestimated.