Properties of amorphous GaN from first-principles simulations

[摘要] Amorphous GaN (a-GaN) models are obtained from first-principles simulations. We compare four a-GaN models generated by melt-and-quench and the computer alchemy method. We find that most atoms tend to be fourfold, and a chemically ordered continuous random network is the ideal structure for a-GaN albeit with some coordination defects. Where the electronic structure is concerned, the gap is predicted to be less than 1.0 eV, underestimated as usual by a density functional calculation. We observe a highly localized valence tail and a remarkably delocalized exponential conduction tail in all models generated. 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 seem consistent with experiment.

[关键词] ELECTRICAL-PROPERTIES;ELECTRONIC DEVICES;OPTICAL-PROPERTIES;GALLIUM NITRIDE;THIN-FILMS;PSEUDOPOTENTIALS;MICROCRYSTALLINE;DEPOSITION