Photoluminescence of hexagonal boron nitride: Effect of surface oxidation under UV-laser irradiation

Abstract

We report on the UV laser-induced fluorescence of hexagonal boron nitride (h-BN) following nanosecond laser irradiation under vacuum and in different environments of nitrogen gas and ambient air. The observed fluorescence bands are tentatively ascribed to impurity and mono (V N ) or multiple (m-V N with m ¼ 2 or 3) nitrogen vacancies. A structured fluorescence band between 300 and 350 nm is assigned to impurity-band transition and its complex lineshape is attributed to phonon replicas. An additional band at 340 nm, assigned to V N vacancies on surface, is observed under vacuum and quenched by adsorbed molecular oxygen. UV-irradiation of h-BN under vacuum results in a broad asymmetric fluorescence at $400 nm assigned to m-V N vacancies; further irradiation breaks more B-N bonds enriching the surface with elemental boron. However, no boron deposit appears under irradiation of samples in ambient atmosphere. This effect is explained by oxygen healing of radiation-induced surface defects. Formation of the oxide layer prevents B-N dissociation and preserves the bulk sample stoichiometry. r

Picosecond laser structuration under high pressures: Observation of boron nitride nanorods

“…In agreement with our earlier studies of nanosecond laser irradiation [17][18], the surface darkening is assigned to elementary boron. Amorphous boron a-B is known to exhibit broadband Raman spectra situated in the low-frequency range below 1200 cm -1 [19].…”

“…On the other hand, the lower-energy bands above 4.09 eV belong to impurity and defect absorption. The structured fluorescence band between 300 nm and 350 nm (F) may be assigned to carbon impurities and nitrogen vacancies and its complex lineshape is explained by phonon replica [18]. Earlier, it has been suggested of using the 4.0-eV fluorescence as a measure of the sample purity.…”

Photoluminescence properties of pyrolytic boron nitride

“…Luminescence properties of high purity commercially available hBN microcrystal powders have been largely studied in cathodoluminescence [2][3][4][5] and photoluminescence [6][7][8][9][10][11][12][13][14] experiments. Due to the synthesis methods used, these powders are inherently contaminated by carbon, calcium and oxygen impurities.…”

Spectral and kinetic features of thermoluminescence in hexagonal boron nitride powder after UV-irradiation

“…These potential dosimetric signals are caused by processes with participating of different lattice defects of intrinsic and extrinsic genesis. At present it is established that many features in the behavior of hexagonal and cubic boron nitrides exposed to radiation are dictated by the complexes based on nitrogen vacancies with substitutional oxygen atoms and carbonic impurities (Kubota et al, 2007;Museur et al, 2007;Trinkler et al, 2004). In addition, defects of synthesis or radiation origin have similar spectral parameters and are to be taken into account while analyzing induced luminescence processes.…”