The electronic properties of zinc-blende GaN, wurtzite GaN and pnma-GaN crystals under pressure

In this study, electronic properties such as the band structure, total density of state (TDOS) and partial density of states (PDOS) of zinc-blende GaN, wurtzite GaN and pnma-GaN crystals are explored through first-principles calculations within the generalized gradient approximation (GGA), and the influence of hydrostatic pressures on the electronic properties are also researched. Results show that the three GaN compounds are all semiconductors with a direct band gap. Although the band gap increases monotonically with the increase of hydrostatic pressure, the hydrostatic pressure has limited effect on the hybridization of valence band and conduction band. In addition, under the same pressure, the band gap of wurtzite GaN is slightly larger than that of the others. Further, calculation results also show that TDOSs of the three compounds are obviously different, and the increase in pressure reduces the peaks of both TDOSs and PDOSs.