Yang Shuai, Sui Fengrui, Liu Yucheng, Qi Ruijuan, Feng Xiaoyu, Dong Shangwei, Yang Pingxiong, Yue Fangyu
Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China.
Nanoscale. 2023 Aug 17;15(32):13297-13303. doi: 10.1039/d3nr02678g.
Low-symmetric GeTe semiconductors have attracted wide-ranging attention due to their excellent optical and thermal properties, but only a few research studies are available on their in-plane optical anisotropic nature that is crucial for their applications in optoelectronic and thermoelectric devices. Here, we investigate the optical interactions of anisotropy in GeTe using polarization-resolved Raman spectroscopy and first-principles calculations. After determining both armchair and zigzag directions in GeTe crystals by transmission electron microscopy, we found that the Raman intensity of the two main vibrational modes had a strong in-plane anisotropic nature; the one at ∼88.1 cm can be used to determine the crystal orientation, and the other at ∼124.6 cm can reveal a series of temperature-dependent phase transitions. These results provide a general approach for the investigation of the anisotropy of light-matter interactions in low-symmetric layered materials, benefiting the design and application of optoelectronic, anisotropic thermoelectric, and phase-transition memory devices based on bulk GeTe.
低对称性的GeTe半导体因其优异的光学和热学性质而受到广泛关注，但关于其面内光学各向异性性质的研究却很少，而这种性质对于其在光电器件和热电器件中的应用至关重要。在此，我们使用偏振分辨拉曼光谱和第一性原理计算来研究GeTe中各向异性的光学相互作用。通过透射电子显微镜确定了GeTe晶体中的扶手椅方向和锯齿方向后，我们发现两种主要振动模式的拉曼强度具有很强的面内各向异性性质；约88.1 cm-1处的模式可用于确定晶体取向，而约124.6 cm-1处的模式可揭示一系列与温度相关的相变。这些结果为研究低对称性层状材料中光与物质相互作用的各向异性提供了一种通用方法，有利于基于块状GeTe的光电器件、各向异性热电器件和相变存储器件的设计与应用。
