Temperature dependence of the excitonic energy band gap in In(Ga)As nanostructures

We analyzed the temperature-dependent variation of the peak energies in the photoluminescence of InAs/GaAs quantum dots and InAs/In0.2Ga0.8As/GaAs quantum dots in an asymmetric well. The InAs dots were grown by using migration-enhanced molecular beam epitaxy. The peak emission energies decreased monotonously with increasing temperature over the range of measurements from 13 K to 225 K. The temperature dependence of the peak energy was successfully fitted with two analytic models, namely, the phenomenological Varshni equation and the semi-empirical Fan equation based on electron-phonon statistics, respectively. The physical meaning of the Varshni coefficients is discussed in terms of the phonon energy and the strain in the nanostructures.