Origin of the annealing-induced blue-shift in GaAsSbN

Effects of the thermal annealing on the optical and structural properties of dilute nitride GaAsSbN epilayers, coherently grown on GaAs substrates by gas-source molecular beam epitaxy, have been investigated. Blue shift in the energy gap of the samples was observed when the annealing temperature was higher than 750degC. Through the analyses on the below energy gap absorption, photoluminescence, and GaN local vibration mode absorption of the samples, we attribute the blue shift to the improvement in the composition homogeneity and the change of the second-nearest-neighboring atoms to the N atoms.