Electronic Band Transitions in γ-Ge3N4

Electronic band structure in germanium nitride having spinel structure, gamma-Ge3N4, was examined using two spectroscopic techniques, cathodoluminescence and synchrotron-based photoluminescence. The sample purity was confirmed by x-ray diffraction and Raman analyses. The spectroscopic measurements provided first experimental evidence of a large free exciton binding energy D-e approximate to 0.30 eV and direct interband transitions in this material. The band gap energy E-g = 3.65 +/- 0.05 eV measured with a higher precision was in agreement with that previously obtained via XES/XANES method. The screened hybrid functional Heyd-Scuseria-Ernzerhof (HSE06) calculations of the electronic structure supported the experimental results. Based on the experimental data and theoretical calculations, the limiting efficiency of the excitation conversion to light was estimated and compared with that of w-GaN, which is the basic material of commercial light emitting diodes. The high conversion efficiency, very high hardness and rigidity combined with a thermal stability in air up to similar to 700 degrees C reveal the potential of gamma-Ge3N4 for robust and efficient photonic emitters.

Automated summary

The electronic band structure of gamma-Ge3N4 was examined using spectroscopic techniques, showing potential as efficient photonic emitters with high thermal stability. The experimental results were supported by theoretical calculations, and the material's high conversion efficiency and robustness were compared with w-GaN, a basic material for commercial LED.