Determination of the Temperature Dependence of the Band Gap Energy of Semiconductors from Transmission Spectra

Abstract

A method to determine the temperature dependence of the band gap energy, E g(T), of semiconductors from their measured transmission spectra is described. A relationship between the band gap energy and the energy corresponding to the peak of the spectral derivative is found for InAs and validated for III–V and II–VI binary semiconductors (InAs, InP, GaAs, GaP, ZnSe, and CdTe). Band gap energies obtained using this method are within 1% of previously published results over a temperature range of 80 K to 650 K. The same method was also applied to two bulk ternary semiconductor alloys (In x Ga1−x As and InAs1−y P y ) for several compositions. Predicted results compared well with thin-film measurements available in the literature. A separate technique for determining E g is also reported, using thickness-dependent transmission spectra. Finally, the thermooptic coefficient (dn/dT) is determined using the derivative of the band gap energy with respect to temperature (dE g/dT) and is compared with direct experimental measured results.