Photoluminescence line shape in degenerate semiconductor quantum wells

Abstract

A microscopic theory and data are presented for the steady-state photoluminescence line shape at low lattice temperatures in modulation-doped degenerate direct-band-gap semiconductor quantum wells which are excited by a low-intensity cw laser. Electron-hole recombinations occur through direct as well as impurity-assisted (indirect) processes. In our theoretical model the photoluminescence linewidths and spectral shifts arise primarily from ionized-impurity scattering of the majority and minority carriers with smaller contributions from the thermal distribution of the carriers. The dependencies of the line shape on the doping configuration (e.g., space-layer thickness) and the carrier temperature are studied. The theory yields good agreement with the line shape of luminescence data from the modulation-doped n-type and p-type strained ${\mathrm{In}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$/GaAs quantum wells with no adjustable parameters.