Abstract Two-dimensional (2D) transition-metal dichalcogenides such as WS2 have attracted an increasing attention in recent years due to their potentials in electronic and optical applications. It is well known that the properties of these 2D systems are sensitive to their surroundings especially substrates. In this paper, we have investigated the effects of sapphire and SiO2/Si substrates on the optical properties of monolayer WS2 using temperature-dependent Raman spectrum, power-dependent and time-resolved photoluminescence (PL). The related results demonstrate substrates exert profound impacts on the Raman and PL properties of WS2. In comparison with the WS2/sapphire sample, charge doping effect contributes to the higher first-order temperature coefficient of A 1 g mode and larger trion binding energy obtained in the WS2/SiO2/Si sample. Both deduced decay times τ0 and τ1of the WS2/sapphire sample, which correspond to the lifetime of trions and excitons, respectively, are much larger than those of the WS2/SiO2/Si sample. The exploration of the nonlinear optical properties of monolayer WS2 on different substrates provides significant guidance for future device design since the related devices will be used under various surroundings and excitation power density.

中文翻译：

---

基材对单层WS2光学性能的影响

摘要 近年来，二维 (2D) 过渡金属二硫属化物如 WS2 因其在电子和光学应用中的潜力而受到越来越多的关注。众所周知，这些 2D 系统的特性对其周围环境特别是基底敏感。在本文中，我们使用温度相关拉曼光谱、功率相关和时间分辨光致发光 (PL) 研究了蓝宝石和 SiO2/Si 衬底对单层 WS2 光学性能的影响。相关结果表明底物对 WS2 的拉曼和 PL 特性产生深远的影响。与WS2/蓝宝石样品相比，电荷掺杂效应有助于在WS2/SiO2/Si 样品中获得更高的A 1 g 模式的一阶温度系数和更大的trion 结合能。WS2/蓝宝石样品推导出的衰减时间 τ0 和 τ1 分别对应于三重子和激子的寿命，远大于 WS2/SiO2/Si 样品的衰减时间。由于相关器件将在各种环境和激发功率密度下使用，因此对不同衬底上单层 WS2 的非线性光学特性的探索为未来的器件设计提供了重要指导。