Jiang Hanjun, Zheng Lu, Wang Jing, Xu Manzhang, Gan Xuetao, Wang Xuewen, Huang Wei
Frontiers Science Center for Flexible Electronics (FSCFE) & Shaanxi Institute of Flexible Electronics (SIFE), Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, 710072, China.
Shaanxi Key Laboratory of Flexible Electronics (KLoFE), Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, 710072, China.
Nanoscale. 2021 Nov 11;13(43):18103-18111. doi: 10.1039/d1nr05725a.
Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have received much attention in nonlinear optical applications due to their unique crystal structures and second harmonic generation (SHG) efficiency. However, SHG signals in TMDs show a layer-dependent behavior, consistent with the presence (absence) of inversion symmetry in even-layer (odd-layer) of TMDs. Herein, we synthesized monolayer and bilayer 2H and 3R phase vanadium (V)-doped MoS crystal. Raman spectroscopy, XPS, and STEM were used to identify the chemical composition and crystalline structure of as-grown nanoflakes. SHG measurement was used to research the symmetry of V-doped MoS crystals with different stacking orders. Significantly, the SHG efficiency in bilayer 2H phase V-doped MoS is equivalent to the 3R phase, indicating an inversion symmetry broken lattice structure caused by the V substitute for Mo sites. This study will be conducive to promote the development of promising nonlinear optical devices based on 2D material.
二维（2D）层状过渡金属二硫属化物（TMDs）因其独特的晶体结构和二次谐波产生（SHG）效率，在非线性光学应用中备受关注。然而，TMDs中的SHG信号表现出与层数相关的行为，这与TMDs偶数层（奇数层）中存在（不存在）反演对称性一致。在此，我们合成了单层和双层的2H和3R相钒（V）掺杂的MoS晶体。利用拉曼光谱、X射线光电子能谱（XPS）和扫描透射电子显微镜（STEM）来确定生长的纳米片的化学成分和晶体结构。通过SHG测量来研究不同堆叠顺序的V掺杂MoS晶体的对称性。值得注意的是，双层2H相V掺杂MoS中的SHG效率与3R相相当，这表明V替代Mo位点导致了反演对称性破缺的晶格结构。这项研究将有助于推动基于二维材料的有前景的非线性光学器件的发展。
