Temperature-dependent photoluminescence of GaN grown on β-Si3N4/Si (1 1 1) by plasma-assisted MBE

►High quality GaN epitaxial layer was grown on β-Si3N4/Si (1 1 1) by plasma-assisted MBE. ►The temperature-dependent PL spectra showed an 'S-like' shape of free exciton emission peaks. ►The activation energy of the free exciton was also evaluated to be ∼27.8±0.7 meV. ►The silicon nitride layer effectively prevents Si diffusion from the substrate to GaN epilayers. ►The tensile stress in GaN film calculated by the thermal stress model.