Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8573, Japan.
Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan.
Molecules. 2023 Feb 16;28(4):1896. doi: 10.3390/molecules28041896.
Two-dimensional materials have wide ranging applications in electronic devices and catalysts owing to their unique properties. Boron-based compounds, which exhibit a polymorphic nature, are an attractive choice for developing boron-based two-dimensional materials. Among them, rhombohedral boron monosulfide (r-BS) has recently attracted considerable attention owing to its unique layered structure similar to that of transition metal dichalcogenides and a layer-dependent bandgap. However, experimental evidence that clarifies the charge carrier type in the r-BS semiconductor is lacking. In this study, we synthesized r-BS and evaluated its performance as a semiconductor by measuring the Seebeck coefficient and photo-electrochemical responses. The properties unique to p-type semiconductors were observed in both measurements, indicating that the synthesized r-BS is a p-type semiconductor. Moreover, a distinct Fano resonance was observed in Fourier transform infrared absorption spectroscopy, which was ascribed to the Fano resonance between the E(2) (TO) phonon mode and electrons in the band structures of r-BS, indicating that the p-type carrier was intrinsically doped in the synthesized r-BS. These results demonstrate the potential future application prospects of r-BS.
二维材料因其独特的性质在电子器件和催化剂中有广泛的应用。由于其多晶型的性质，硼基化合物是开发硼基二维材料的理想选择。其中，三方相硼单硫化物（r-BS）因其类似于过渡金属二卤化物的独特层状结构和与层相关的能隙，最近引起了相当大的关注。然而，缺乏实验证据来澄清 r-BS 半导体中的电荷载流子类型。在这项研究中，我们合成了 r-BS，并通过测量塞贝克系数和光电化学响应来评估其作为半导体的性能。这两种测量都观察到了 p 型半导体的独特性质，表明合成的 r-BS 是一种 p 型半导体。此外，在傅里叶变换红外吸收光谱中观察到了明显的 Fano 共振，这归因于 r-BS 能带结构中 E(2)（TO）声子模式和电子之间的 Fano 共振，表明在合成的 r-BS 中存在本征掺杂的 p 型载流子。这些结果表明了 r-BS 的潜在未来应用前景。
