Band structures for Ge3N4 polymorphs studied by DFT-LDA and GWA

Ab initio band structures for α-Ge3N4, β-Ge3N4, and γ-Ge3N4 are calculated using density functional theory with the local density approximation. The band energies of special k-points in the Brillouin zone are corrected using the GW approximation to accurately predict the band gap energy. The γ-Ge3N4 has a direct band gap of 3.462 eV, indicating its promising applications as a wide-band-gap semiconductor for short-wavelength optoelectronics.