Huang Yuanyuan, Yao Zehan, He Chuan, Zhu Lipeng, Zhang Longhui, Bai Jintao, Xu Xinlong
Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics and Photon-Technology, Northwest University, Xi'an 710069, People's Republic of China.
J Phys Condens Matter. 2019 Apr 17;31(15):153001. doi: 10.1088/1361-648X/ab00c0. Epub 2019 Jan 22.
Surfaces and interfaces are of particular importance for optoelectronic and photonic materials as they are involved in many physical and chemical processes such as carrier dynamics, charge transfer, chemical bonding, transformation reactions and so on. Terahertz (THz) emission spectroscopy provides a sensitive and nondestructive method for surface or interface analysis of advanced materials ranging from graphene to transition metal dichalcogenides, topological insulators, hybrid perovskites, and mixed-dimensional heterostructures based on 2D materials. In this review paper, we start with the THz radiation mechanisms under ultrafast laser excitation. Then we concentrate on the recent progresses of THz emission spectroscopy on the surface and interface properties of advanced materials, including transient surface photocurrents, surface nonlinear polarization, surface states, interface potential, and gas molecule adsorption/desorption processes. This novel spectroscopic method can not only promote the development of new and compact THz sources, but also provide a nondestructive optical method for surface and interface characterization of photocurrent and nonlinear polarization dynamics of materials.
表面和界面对于光电子和光子材料尤为重要，因为它们参与了许多物理和化学过程，如载流子动力学、电荷转移、化学键合、转化反应等。太赫兹（THz）发射光谱法为从石墨烯到过渡金属二硫属化物、拓扑绝缘体、混合钙钛矿以及基于二维材料的混合维异质结构等先进材料的表面或界面分析提供了一种灵敏且无损的方法。在这篇综述文章中，我们首先介绍超快激光激发下的太赫兹辐射机制。然后我们专注于太赫兹发射光谱在先进材料表面和界面性质方面的最新进展，包括瞬态表面光电流、表面非线性极化、表面态、界面电势以及气体分子吸附/解吸过程。这种新颖的光谱方法不仅可以推动新型紧凑型太赫兹源的发展，还能为材料光电流和非线性极化动力学的表面和界面表征提供一种无损光学方法。
