Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal
Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal
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DOI：
10.1038/nmat1134
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发表时间：
2004-06-01
期刊：
影响因子：
41.2
通讯作者：
Kanda, H
中科院分区：
文献类型：
--
作者：
Watanabe, K;Taniguchi, T;Kanda, H
对紧凑型紫外激光设备的需求正在增加，因为它们在光存储、消毒、灭菌、眼科手术和纳米手术等应用中至关重要。许多研究人员正致力于寻找比GaN更大带隙的材料。在这里，我们表明六方氮化硼（hBN）是此类激光器件的一种有前途的材料，因为它在紫外区具有直接带隙。在高温高压条件下，我们得到了一个纯的hBN单晶，它在215 nm附近有一个主发光峰和一系列类s激子吸收带，证明它是一种直接带隙材料。在215 nm的室温紫外激光由加速电子激发的证据提供的增强和缩小的纵向模式，阈值行为的激发电流的依赖性的发射强度，和远场图案的横向模式。
The demand for compact ultraviolet laser devices is increasing, as they are essential in applications such as optical storage, photocatalysis, sterilization, ophthalmic surgery and nanosurgery. Many researchers are devoting considerable effort to finding materials with larger bandgaps than that of GaN. Here we show that hexagonal boron nitride (hBN) is a promising material for such laser devices because it has a direct bandgap in the ultraviolet region. We obtained a pure hBN single crystal under high-pressure and high-temperature conditions, which shows a dominant luminescence peak and a series of s-like exciton absorption bands around 215 nm, proving it to be a direct-bandgap material. Evidence for room-temperature ultraviolet lasing at 215 nm by accelerated electron excitation is provided by the enhancement and narrowing of the longitudinal mode, threshold behaviour of the excitation current dependence of the emission intensity, and a far-field pattern of the transverse mode.