Temperature dependence of the direct band gap energy and donor–acceptor transition energies in Be-doped GaAsSb lattice matched to InP

Abstract

The direct band energy (Eg) and donor–acceptor (D,A) transition energies are mapped as a function of temperature for Be-doped GaAsSb lattice matched to InP. Photoluminescence (PL) measurements over the temperature range 2 K≤T≤300 K yield two emission peaks, one of lower intensity and one of higher intensity. The lower intensity peak is believed to be Be related, while the higher intensity peak is from residual impurities. The emission energies of both PL peaks increase linearly with respect to the logarithm of excitation intensity, indicating the peaks are (D,A) transitions. Measurement of Eg was achieved using optical absorption spectroscopy over the range 14 K≤T≤300 K. A least squares fit of the absorption data using the Varshni equation produces a closed form expression for Eg(T) with coefficients α=13.5×10−4 eV/K, and β=135 K.