Metalorganic vapor phase epitaxy growth and photoluminescence properties of cubic AlxGa1−xN

We have grown cubic AlxGa1−xN (0<x<0.25) films on GaAs (100) substrates by metalorganic vapor phase epitaxy. A strong excitonic transition, as well as a donor–acceptor pair transition and a deep-level emission, was observed in the photoluminescence spectra at 5 K in all the samples. With increasing Al fraction, all the emission lines shift to higher energy, nevertheless, with different shift rates. The temperature-dependent photoluminescence spectra show that the behavior of the donor–acceptor pair transition varied with Al fraction; at higher Al concentrations, the donor–acceptor pair transition tends to transform to a free-electron to acceptor transition and survive even at room temperature. This can also explain the energy shift to higher energy with increasing temperature for this emission line.