Electronic band transitions in γ-Ge3N4

다국어 초록 (Multilingual Abstract)

Electronic band structure in germanium nitride having spinel structure, γ-Ge 3 N 4 , was examined using two spectroscopictechniques, cathodoluminescence and synchrotron-based photoluminescence. The sample purity was confi rmed by x-raydiff raction and Raman analyses. The spectroscopic measurements provided fi rst experimental evidence of a large free excitonbinding energy D e ≈0.30 eV and direct interband transitions in this material. The band gap energy E g = 3.65 ± 0.05 eVmeasured with a higher precision was in agreement with that previously obtained via XES/XANES method. The screenedhybrid functional Heyd–Scuseria–Ernzerhof (HSE06) calculations of the electronic structure supported the experimentalresults. Based on the experimental data and theoretical calculations, the limiting effi ciency of the excitation conversion tolight was estimated and compared with that of w-GaN, which is the basic material of commercial light emitting diodes. Thehigh conversion effi ciency, very high hardness and rigidity combined with a thermal stability in air up to ~ 700 °C reveal thepotential of γ-Ge 3 N 4 for robust and effi cient photonic emitters.

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