Well-width dependence of the in-plane effective mass and quantum lifetime of electrons in multiple quantum wells

Abstract

The electronic properties of modulation-doped multiple quantum wells (MWQ) with well width in the range between 51 and 145 Å have been investigated by using the Shubnikov - de Haas (SdH) oscillations technique. The carrier density and the Fermi energy have been determined from the period of the SdH oscillations. The in-plane effective mass and the quantum lifetime of 2D electrons have been obtained from the temperature and magnetic field dependences of the SdH amplitude. For narrow MQW samples (, 75 and 78 Å), increases with decreasing ; for the samples with and 145 Å, is approximately equal to that of electrons in bulk GaAs. The values obtained for show no clear well-width dependence and suggest that interface roughness is the dominating scattering mechanism in MQWs.