Wang Peng, Wang Jian, Zheng Yun, Shi Hongyan, Sun Xiudong, Liu Wenjun, Gao Bo
Institute of Modern Optics, School of Physics, Key Laboratory of Micro-Nano Optoelectronic Information System, Ministry of Industry and Information Technology, Key Laboratory of Micro-Optics and Photonic Technology of Heilongjiang Province, Harbin Institute of Technology, Harbin 150001, China.
Phys Chem Chem Phys. 2021 Aug 28;23(32):17265-17270. doi: 10.1039/d1cp02248b. Epub 2021 Aug 4.
Monolayer semiconducting two-dimensional (2D) materials are strongly emerging materials for exploring the spin-valley coupling effect and fabricating novel optoelectronic devices due to their unique structural symmetry and band structures. Due to their atomic thickness, their excitonic optical response is highly sensitive to the dielectric environment. In this work, we present a novel approach to reversibly modulate the optical properties of monolayer molybdenum disulfide (MoS) via changing the dielectric properties of the substrate by laser irradiation and thermal annealing. We chose LiNbO as the substrate and recorded the PL spectra of monolayer MoS on LiNbO substrates with positive (P) and negative (P) ferroelectric polarities. A distinct PL intensity of the A peak was observed due to opposite doping by surface charges. Under light irradiation, the PL intensity of monolayer MoS on P FeO-doped LiNbO gradually decreased with time due to the reduction of intrinsic p-doping, which originated from the drift of photo-excited electrons under a spontaneous polarization field and accumulation on the surface. The PL intensity was found to be restored by thermal annealing which could erase the charge redistribution. This study provides a strategy to reversibly modulate the optical properties of monolayer 2D materials on top of ferroelectric materials.
单层半导体二维（2D）材料因其独特的结构对称性和能带结构，成为探索自旋-谷耦合效应和制造新型光电器件的新兴材料。由于其原子厚度，它们的激子光学响应对介电环境高度敏感。在这项工作中，我们提出了一种新颖的方法，通过激光辐照和热退火改变衬底的介电特性，来可逆地调制单层二硫化钼（MoS）的光学特性。我们选择LiNbO作为衬底，并记录了具有正（P）和负（P）铁电极性的LiNbO衬底上单层MoS的光致发光（PL）光谱。由于表面电荷的相反掺杂，观察到A峰有明显的PL强度。在光照射下，由于本征p型掺杂的减少，P FeO掺杂的LiNbO上单层MoS的PL强度随时间逐渐降低，这源于光激发电子在自发极化场下的漂移并在表面积累。发现通过热退火可以恢复PL强度，热退火可以消除电荷重新分布。这项研究提供了一种在铁电材料之上可逆地调制单层二维材料光学特性的策略。
