Photoluminescence from electron-hole plasmas confined in Si/Si1−xGex/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.