Terahertz emission from layered GaTe crystal due to surface lattice reorganization and in-plane noncubic mobility anisotropy

作     者：Jiangpeng Dong Kevin-P. Gradwohl Yadong Xu Tao Wang Binbin Zhang Bao Xiao Christian Teichert Wanqi Jie 

作者机构：State Key Laboratory of Solidification Processing Ministry of Industry and Information Technology (MIIT) Key Laboratory of Radiation Detection Materials and Devices School of Materials and Engineering Northwestern Polytechnical University Xi'an 710072 China Institute of Physics Montanuniversitaet Leoben Leoben 8700 Austria 

出 版 物：《Photonics Research》 (光子学研究（英文版）)

年 卷 期：2019年第7卷第5期

页      面：518-525页

核心收录：

学科分类：07[理学] 0702[理学-物理学] 

基　　金：National Key Research and Development Program of China(2016YFE0115200) Ministry of Industry and Information Technology of the People’s Republic of China(MIIT)(MJ-2017-F-05) Fundamental Research Funds for the Central Universities(3102017zy057,3102018jcc036) Austrian Academic Exchange Service(OAD-WTZ)(CN 02/2016) National Natural Science Foundation of China(NSFC)(51872228) 

主　　题：GaTe crystal surface lattice reorganization in-plane noncubic mobility 

摘      要：In this work, a model based on the optical rectification effect and the photocurrent surge effect is proposed to describe the terahertz emission mechanism of the layered GaTe crystal. As a centrosymmetric crystal, the optical rectification effect arises from the breaking of the inversion symmetry due to lattice reorganization of the crystal’s surface layer. In addition, the photocurrent surge originating from the unidirectional charge carrier diffusion-due to the noncubic mobility anisotropy within the layers-produces terahertz radiation. This is confirmed by both terahertz emission spectroscopy and electric property characterization. The current surge perpendicular to the layers also makes an important contribution to the terahertz radiation, which is consistent with its incident angle dependence. Based on our results, we infer that the contribution of optical rectification changes from 90%under normal incidence to 23% under a 40° incidence angle. The results not only demonstrate the terahertz radiation properties of layered GaTe bulk crystals, but also promise the potential application of terahertz emission spectroscopy for characterizing the surface properties of layered materials.