Photoluminescence investigation of the properties of GaAsSb in the dilute Sb regime

GaAsSb epitaxial layers are grown using liquid-phase epitaxy (LPE) technique over < 100 > oriented GaAs substrates. The layers contain up to 1.84% Sb, as estimated from high-resolution X-ray diffraction (HRXRD) measurements. Detailed photoluminescence (PL) studies are made on the as-grown and high-temperature-annealed layers to reveal various electronic transitions in the materials. Excitation power-dependent PL measurements are done to investigate the origin of each of the transitions. The bandgap energy, obtained from PL, shows a reduction of approximately 17 meV per at% increase in Sb content, which agrees well with the bandgap reduction, calculated with the band anticrossing (BAC) model. Analysis of the temperature-dependent PL data, using Bose–Einstein model, indicates that both the electron–phonon interaction and the average phonon temperatures strongly depend on the Sb content in GaAsSb.