Investigation of deep level traps in dilute GaAsN layers grown by liquid phase epitaxy

Abstract

Dilute GaAsN layers are grown by liquid phase epitaxy (LPE) technique, using polycrystalline GaN as the source of nitrogen. A band gap lowering of 100 meV is obtained from low temperature photoluminescence (PL) measurements which correspond to a little more than 0.5% nitrogen in the layer. Using 10 K photocapacitance measurements, a 0.7 eV electron trap is detected in the material which is assigned to an interstitial (N–N) As defect. Annealing of the material at 750 °C for 1 h greatly reduced this trap and new electron traps with activation energies of 0.8 and 0.9 eV are detected. These new traps are suggested to be due to individual nitrogen-related defect complexes, produced by the thermal annihilation of the N–N bond. After a high temperature treatment of the GaAsN growth melt with 0.1 wt.% Er, nitrogen is found to be removed from the layer and no electron trap was detected.