Photoluminescence from electron-hole plasmas confined in Si/Si1−<i>x</i>Ge<i>x</i>/Si quantum wells

Abstract

We report the first observation of photoluminescence from electron-hole plasmas in Si/Si0.8Ge0.2/Si quantum wells. While at liquid helium temperature, luminescence due to shallow bound excitons is observed. At 77 K electron-hole plasma (EHP) luminescence dominates the spectra over a wide range of pump powers. Convolution of the occupied electron and hole densities of states gives an excellent fit to the photoluminescence line shape. A band-gap reduction of up to 15 meV at high carrier densities is observed for wide quantum wells, but no such shift is detected for narrow quantum wells.