Ultraviolet luminescence from hexagonal boron nitride heteroepitaxial layers on Ni(111) grown by flow-rate modulation epitaxy

We report room-temperature (RT) observation of near-band-gap ultraviolet luminescence at a wavelength of 227 nm in cathodoluminescence from h-BN heteroepitaxial layers. The h-BN layers were grown on single crystal Ni(111) substrates by flow-rate modulation epitaxy (FME), which is based on the alternate supply of triethylboron and ammonia. The h-BN layers grown with longer NH₃ supply time exhibit stronger intensity and narrower full width of half maximum (FWHM) of the near-band-gap luminescence. X-ray diffraction measurements reveal that the FWHM of (0002) h-BN X-ray rocking curves decreases with increasing NH₃ supply time. The reduction of lattice defects in h-BN grown by FME with longer NH₃ supply time could be the reason for the improved near-band-gap ultraviolet luminescence at RT.