期刊
JOURNAL OF LUMINESCENCE
卷 127, 期 2, 页码 595-600出版社
ELSEVIER
DOI: 10.1016/j.jlumin.2007.01.024
关键词
hexagonal boron nitride; photoluminescence; surface oxidation; UV-laser irradiation
类别
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 = 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 similar to 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. (C) 2007 Elsevier B.V. All rights reserved.
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