Terahertz emission from 2D nanomaterials
Terahertz emission from 2D nanomaterials
复制标题
DOI：
10.1117/12.2322160
复制
发表时间：
2018-09
期刊：
影响因子：
--
通讯作者：
K. Kushnir;Mengjing Wang;Ying Qin;Guangjiang Li;S. Tongay;K. Koski;L. Titova
中科院分区：
文献类型：
--
作者：
K. Kushnir;Mengjing Wang;Ying Qin;Guangjiang Li;S. Tongay;K. Koski;L. Titova
IV族单硫属化合物属于2D分层材料家族。从理论上预测，第IV族单硫族化合物GeS、GeSe、SnS和SnSe的单层在室温下由于自发极化而表现出大的移位电流。利用THz发射光谱，我们发现在亚μm到几μm厚的多层GeS和GeSe中，由于晶体表面的反转对称性破缺，超短激光脉冲的光激发导致了近单周期的THz脉冲发射。通过表面位移电流的太赫兹发射的实验演示提出了这种层状IV族单硫族化合物作为下一代位移电流光电转换器，非线性光子器件和太赫兹源的候选人。
Group-IV monochalcogenides belong to a family of 2D layered materials. Monolayers of group-IV monochalcogenides GeS, GeSe, SnS and SnSe have been theoretically predicted to exhibit a large shift current owing to a spontaneous electric polarization at room temperature. Using THz emission spectroscopy, we find that above band gap photoexcitation with ultrashort laser pulses results in emission of nearly single-cycle THz pulses due to a surface shift current in multi-layer, sub-μm to few- μm thick GeS and GeSe, as inversion symmetry breaking at the crystal surface enables THz emission by the shift current. Experimental demonstration of THz emission by the surface shift current puts this layered group-IV monochalcogenides forward as a candidate for next generation shift current photovoltaics, nonlinear photonic devices and THz sources.