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. 
Bin Cai and David A. Drabold
cond-mat.dis-nn cond-mat.mtrl-sci