The properties of amorphous GaN

In this paper, we present three amorphous GaN models obtained from the first principles simulation. We find that a chemically ordered continuous random network is the ideal structure for a-GaN. If we exclude the tail states, we predict a 3.0eV optical gap for 64-atom model and 2.3eV for 250-atom models. We observe a highly localized valence tail and a remarkably delocalized exponential conduction tail which we associate with different hybridization in the two tails. Based upon these results, we speculate on potential differences in n and p type doping. The structural origin of tail and defect states is discussed. The vibrational density of states and dielectric function are computed, and are consistent with experiment.