In conventional 3D heterostructures, a gradual potential gradient in constituent layers and an abrupt potential discontinuity at heterointerfaces can appear. Studies of the electrostatic potential in 2D heterostructures require careful characterizations and analyses because the 2D materials have distinct physical characteristics compared with their 3D counterparts. Herein, three kinds of samples are prepared using sulfurization of metal layers on single‐crystalline sapphire substrates: WS₂, MoS₂, and WS₂/MoS₂. The surface potential (V _S) of the samples is measured using Kelvin probe force microscopy. The light‐induced V _S change in the stand‐alone trilayer (3L‐) WS₂ (−63 mV) is much more notable than that in the 3L‐WS₂/3L‐MoS₂ heterostructure (−12 mV). In contrast, the light‐induced V _S change in the stand‐alone 3L‐MoS₂ is positive and very large (≈200 mV). To explain these results, the potential and internal field distributions are proposed for both the stand‐alone (WS₂ and MoS₂) and heterostructure (WS₂/MoS₂) samples. The polarity and magnitude of the internal field depend on the electronic interaction and screening from neighboring 2D layers and underlying substrates. Relative peak shifts of the Raman spectra of the samples are obtained and discussed, with consideration of the internal field effects.

中文翻译：

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在蓝宝石衬底上外延生长的多层WS2 / MoS2异质结构的内部场

在常规的3D异质结构中，可能会出现组成层中的逐渐电势梯度和异质界面处的突然电势不连续性。2D异质结构中静电势的研究需要仔细的表征和分析，因为2D材料与3D材料相比具有独特的物理特性。在此，使用硫化在蓝宝石单晶衬底上的金属层制备了三种样品：WS ₂，MoS ₂和WS ₂ / MoS ₂。表面电位（V_小号样品的）是利用开尔文探针力显微镜测量。光致V _S独立三层（3L）WS ₂（−63 mV）的变化比3L‐WS ₂ / 3L‐MoS ₂异质结构（−12 mV）的变化要明显得多。相反，独立的3L-MoS _2中光诱导的V _S变化是正的并且非常大（≈200mV）。为了解释这些结果，提出了独立（WS ₂和MoS ₂）和异质结构（WS ₂ / MoS ₂）的势场和内部场分布）样品。内部场的极性和大小取决于电子交互作用以及与相邻2D层和下面的基板的屏蔽。考虑到内部场效应，获得并讨论了样品拉曼光谱的相对峰位移。