Electron-phonon scattering in Ga1−xAlxAs quantum-well structures in an electric field

Abstract

Effects of the well width and an electric field on electron-phonon scattering are studied for two kinds of quantum-well structures. One is a symmetrical single quantum well (SSQW) ${\mathrm{Ga}}_{0.6}$ ${\mathrm{Al}}_{0.4}$As/GaAs/${\mathrm{Ga}}_{0.6}$ ${\mathrm{Al}}_{0.4}$As, and the other is an asymmetrical single quantum well (ASQW) ${\mathrm{Ga}}_{0.6}$ ${\mathrm{Al}}_{0.4}$As/GaAs-${\mathrm{Ga}}_{0.8}$ ${\mathrm{Al}}_{0.2}$As/${\mathrm{Ga}}_{0.6}$ ${\mathrm{Al}}_{0.4}$As. Calculated results reveal that for both structures without an electric field, the intrasubband and intersubband scattering rates due to interface phonons, respectively, decrease and increase with increasing well width while those due to confined phonons increase with increasing well width. It is found that the difference between SSQW and ASQW structures results in a significant change of phonon modes and electronic structure and consequently the dependence of scattering rates on an applied electric field is quite different for the two structures, and that the intersubband scattering rates can be considerably changed by applied electric field as the well width is large. The result would be useful for analyzing experimental results and designing some devices in the future.