Multiband Luminescence in Boron Nitride

Abstract

SIMPSON, McCRA W, AND MARTON0.03% of the sample. At the magnification employed, any hole larger than 300 A in diameter would have been noticed. Above this size, we conclude that the 61ms are essentially continuous.It will be noted that improved aperturing of the beam and the deliberate addition of a large incoming beam contamination, while radically changing the elastic distribution, have only minor effects on the characteristic distribution. Moreover, it appears that at angles beyond 4&(10 ' radian the angular dependence of the elastically scattered electrons is less rapid than that of the characteristically scattered electrons.The data for aluminum presented in Fig. 2 were analyzed in an attempt to confirm the dependence of the value of the characteristic energy loss, E, on the scattering angle, 0, reported by Watanabe' and attributed by him and others to the dispersion of plasma waves. The expected dependence is of the form 8=AO'.In a small region between 6 and 12 milliradians, our data show a 0' dependence, although the constant disagrees by 50 j~f rom that of Watanabe. Outside this region, neither the constant nor the exponent agrees with his values.Boron nitride can be excited to luminesce by (1) alternating electric 6elds, (2) ultraviolet photons, or (3) cathode rays. The luminescence, in all cases, has a complex emission spectrum, extending from approximately 2950 A to 6500 A. The relative intensities of the bands in the fine structure are affected by current density with cathode-ray excitation, and by the energy (frequency) of the photons with ultraviolet excitation. The maximum of the photoluminescence emission intensity with temperature occurs at about 875'K, with the luminescence emission intensity falling to 50% of the maximum value at approximately 1375 K.Correspondence of known infrared absorption bands with energy differences in the fine structure in the luminescence suggest vibrational origins for the fine structure. The identities of the excited electronic states have not yet been ascertained, although these may be due to exciton states, impurity states, or surface states.

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.…”

Chemical Vapour Deposition of sp2 Hybridised Boron Nitride

“…Such luminescence investigations showed many bands in the blue and near UV region, but the near bang gap luminescence was not observed [75]. Nevertheless, the width of the band gap was estimated to be not lower than [83,84,85,86].…”

“…Early works on the characterisation of BN mainly include optical characterisation of the material with photoluminescence (1920), cathodoluminescence (1925), electroluminescence (1956) and reflectance [73,74,75]. Such luminescence investigations showed many bands in the blue and near UV region, but the near bang gap luminescence was not observed [75].…”

Spectroscopic investigation on BCNO-based phosphor: photoluminescence and long persistent phosphorescence

“…This result implies that a nonradiative relaxation Energy (eV) process (probably assisted by several lattice phonons) from the electronic level at 4.0 eV (310 nm) to the level at 3.5 eV (350 nm) occurs during the excitation at a wavelength shorter than 300 nm. The origins of the PL behaviour of the h-BN or t-BN and the related materials in this region (300-450 nm) derived from different methods have been primarily assigned to different types of defects [26][27][28], rather than band to band transition. The detailed mechanisms for the emission will be addressed in section 4.…”