Numerical simulation of the temperature dependence of band-edge photoluminescence and electroluminescence in strained-Si1-xGex/Si heterostructures

The temperature dependence of band-edge photoluminescence (PL) and electroluminescence (EL) of Si_1-xGe_x/Si heterostructures was simulated using a two-carrier device simulator. The device simulator was used to determine electrically and optically excited carrier profiles, from which light emission was computed. The simulations confirmed an earlier result that PL intensity at high temperature (> 150K) is controlled by surface recombination. Furthermore, it was found that the difference in measured temperature dependence between PL and EL experiments is due to (i) the EL experiments being performed at a much higher total injection rate and (ii) the heavily doped, buried contact layers in EL structures (p-i-n diodes) effectively blocking carriers from diffusing into the substrate and away from the Si_1-xGe_x layer.