Chou Sheng-Lung, Lin Meng-Yeh, Huang Tzu-Ping, Lin Shu-Yu, Yang Min-Zhen, Lee Yin-Yu, Wu Yu-Jong
National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan.
Department of Applied Chemistry and Institute for Molecular Science, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 Apr 5;270:120849. doi: 10.1016/j.saa.2021.120849. Epub 2022 Jan 3.
Hexagonal boron nitrides (hBNs) have a very high luminescence efficiency and are promising materials for deep-UV emitters. Although intense deep-UV emissions have been recorded in various forms of hBN excited by photons or energetic electrons, information on the electronic structure of the conduction band has been derived mainly from theoretical works. Therefore, there is a lack of high-resolution absorption data in the far-UV region. In this study, the far-UV absorption spectra of chemical-vapor-deposition-grown mono- and multilayer hBNs were recorded at 10 and 298 K. In addition to the previously reported band at 6.10 eV, two absorption bands at 6.82 and 8.86 eV were observed for the first time in thin-film hBN. Furthermore, excitation of the hBN thin film samples with 6.89-eV photons revealed intense emission peaks at 6.10 (mono) and 5.98 (multi) eV with a bandwidth of ∼0.7 eV. Comparing the absorption and photoluminescence data, we believe that both direct and indirect transitions occur in the radiative processes.
六方氮化硼（hBNs）具有非常高的发光效率，是用于深紫外发光体的有前景的材料。尽管在光子或高能电子激发的各种形式的hBN中都记录到了强烈的深紫外发射，但导带电子结构的信息主要来自理论研究。因此，远紫外区域缺乏高分辨率的吸收数据。在本研究中，在10 K和298 K下记录了化学气相沉积生长的单层和多层hBN的远紫外吸收光谱。除了先前报道的6.10 eV处的能带外，在薄膜hBN中首次观察到6.82和8.86 eV处的两个吸收带。此外，用6.89 eV光子激发hBN薄膜样品，在6.10（单层）和5.98（多层）eV处显示出强烈的发射峰，带宽约为0.7 eV。比较吸收和光致发光数据，我们认为辐射过程中同时发生直接和间接跃迁。
