Room-Temperature Deep-UV Photoluminescence from Low-Dimensional Hexagonal Boron Nitride Prepared Using a Facile Synthesis

Abstract

Identification and evaluation of defect levels in low-dimensional materials is an important aspect in quantum science. In this article, we report a facile synthesis method of low-dimensional hexagonal boron nitride (h-BN) and study light emission characteristics due to the defects. The thermal annealing procedure is optimized to obtain clean multilayered h-BN as revealed by transmission electron microscopy. UV–vis spectroscopy shows the optical energy gap of 5.28 eV, which is comparable to the reported energy gap for exfoliated, clean h-BN samples. X-ray photoelectron spectroscopy reveals the location of the valence band edge at 2 eV. The optimized synthesis route of h-BN generates two kinds of defects, which are characterized using room-temperature photoluminescence (PL) measurements. The defects emit light at 4.18 eV [deep-UV (DUV)] and 3.44 eV (UV) photons. The intensity of PL has an oscillatory dependence on the excitation energy for the defect emitting DUV light. A series of spectral lines are observed with the energy ranging between 2.56 and 3.44 eV. The average peak-to-peak energy separation is about 125 meV. The locations of the spectral lines can be modeled using Franck–Condon-type transition and associated with displaced harmonic oscillator approximation. Our facile route gives an easier approach to prepare clean h-BN, which is essential for classical two-dimensional material-based electronics and single-photon-based quantum devices.

One‐Pot Synthesis of Luminescent and Photothermal Carbon Boron‐Nitride Quantum Dots Exhibiting Cell Damage Protective Effects

“…A gradually decrease of the optical bandgap by increasing the carbon content is reported in literature for exfoliated BN nanostructures. [38,39] Additionally, the optical bandgap at about E g2 = 4.2 eV is reasonably ascribable to carbon-substituted BNQDs as reported in literature [40,41] and recently by Thamankar and co-workers. [39] In summary, the red-shifted optical absorption bands above 350 nm observed for the BNQDs in comparison with the bare-BNs, undoubtedly supported the formation of carbon-functionalized BNQDs structures.…”

Neutron Irradiation Effects on Boron Nitride-Based Ceramics for Use in X-ray Detection

“…BN is a white, crystalline ceramic, commonly with a hexagonal crystal structure similar to that of graphite. − Boron nitride has a wide range of applications, e.g ., lubricant, electrical insulators, thermal conductors, and deep ultraviolet (UV) emitter . Boron nitride is a well-known wide band gap semiconductor and has been successfully introduced for deep UV and neutron detection, benefiting from the decent charge transport properties (high sensitivity) and high resistivity (low noise level), making them ideal candidates for photodetection. − For instance, Kaushik et al reported deep-ultraviolet photodetectors based on hexagonal boron nitride nanosheets and enhanced the device performance by localized surface plasmon resonance with Al nanoparticles . Liu and co-authors fabricated high-performance deep ultraviolet photodetectors based on few-layer hexagonal boron nitride and achieved ultra-high on/off ratio of >10 3 .…”