Temperature dependence of the indirect energy gap in crystalline silicon

The photoluminescence spectra of crystalline silicon samples are measured for temperatures below 1000 K. The optical transitions are analyzed in terms of excitonic and band-to-band transitions. From the modeling of the line shape we are able to determine the fundamental indirect band gap for temperatures up to 750 K. The temperature dependence follows the Varshni equation with Eg(0)=1.1692 eV, α=(4.9±0.2)×10−4 eV/K and β=(655±40) K.