Electron–acoustic phonon interaction in semiconductor nanostructures: Role of deformation variation of electron effective mass

We demonstrate that the phonon-induced variation of electron effective mass gives a substantial contribution to the electron–acoustic-phonon interaction in semiconductor nanostructures. Calculations are carried out for electrons in a quantum well (QW) and a quantum wire (QWR) of III-V heterostructure materials. This mechanism gives rise to an interference effect in electron scattering with longitudinal acoustic phonons via the deformation potential and allows the electrons to interact with transverse acoustic phonons. Due to these peculiarities, the additional channel of scattering can either increase or decrease the total scattering rate. For a given semiconductor, the modified scattering constant has been shown to depend on the dimensionality of the electron gas, the size and the shape of the nanostructure, and on the temperature. The scattering constants for intrasubband transitions in QW’s and QWR’s are different for the electron energy and momentum relaxation. For narrow QW’s or flattened QWR’s, modification of the commonly used bulk deformation potential interaction at low temperatures originates mainly due to interaction with transverse acoustic phonons. For GaAs QW of 50 Å width, the ratio of the total relaxation rate of the electron energy to that from the bulk deformation potential coupling is about 0.65 for the temperature 4 K and 1.7 for 20 K.