In this study, a multilayered van der Waals (vdW) heterostructure, HfS₂/MoTe₂, was modeled and simulated using density functional theory (DFT). It was found that the multilayers (up to 7 layers) are typical indirect bandgap semiconductors with an indirect band gap varying from 0.35 eV to 0.51 eV. The maximum energy value of the valence band (VBM) and the minimum energy value of the conduction band (CBM) of the heterostructure were found to be dominated by the MoTe₂ layer and the HfS₂ layer, respectively, characterized as type-II band alignment, leading to potential photovoltaic applications. Optical spectra analysis also revealed that the materials have strong absorption coefficients in the visible and ultraviolet regions, which can be used in the detection of visible and ultraviolet light. Under an external strain perpendicular to the layer plane, the heterostructure exhibits a general transition from semiconductor to metal at a critical interlayer-distance of 2.54 Å. The carrier effective mass and optical properties of the heterostructures can also be modulated under external strain, indicating a good piezoelectric effect in the heterostructure.

中文翻译：

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HfS2/MoTe2 vdW异质结构：基于第一性原理计算的能带结构和应变工程

在这项研究中，使用密度泛函理论 (DFT)对多层范德华 (vdW) 异质结构HfS ₂ /MoTe _{2进行了建模和模拟。}发现多层（最多7层）是典型的间接带隙半导体，间接带隙从0.35 eV到0.51 eV不等。发现异质结构的价带的最大能量值(VBM)和导带的最小能量值(CBM)由MoTe ₂层和HfS _2支配层，分别表征为II型带对准，导致潜在的光伏应用。光谱分析还表明，该材料在可见光和紫外光区域具有很强的吸收系数，可用于可见光和紫外光的检测。在垂直于层平面的外部应变下，异质结构在 2.54 Å 的临界层间距离处表现出从半导体到金属的一般转变。异质结构的载流子有效质量和光学性质也可以在外部应变下进行调制，表明异质结构具有良好的压电效应。