MoSe₂ and Bi₂Se₃ are two kinds of 2D materials that are gradually receiving more attention because of their unique electronic and optical properties. Herein, a Bi₂Se₃/MoSe₂ van der Waals heterojunction (vdWH) is constructed and the electronic and optical properties of the heterojunction are calculated using first-principles calculations. The effects of the external electric field and the interlayer distance on the electronic properties of the heterojunction are also studied. The calculated results show that the inherent Bi₂Se₃/MoSe₂ vdWH has a type-2 band alignment with a very small indirect bandgap (28 meV). It also has strong spin–orbit coupling effects, and the characteristics of Zeeman splitting and Rashba splitting are observed at the same time. Both applying an external electric field and changing the interlayer distance can effectively modulate the band structure of the heterojunction; these modulation methods can change the band alignment of the vdWH from type-2 to type-3 or even type-1, and the bandgap type can be changed from indirect to direct. The infrared absorption of the heterojunction is much higher than that of Bi₂Se₃ and MoSe₂. All the calculation results show that the Bi₂Se₃/MoSe₂ vdWH has good application prospects in optoelectronic and spintronic devices.

中文翻译：

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Bi2Se3/MoSe2异质结电子和光学性质的第一性原理研究

MoSe ₂和Bi ₂ Se ₃是两种二维材料，因其独特的电子和光学特性而逐渐受到关注。在此，构建了 Bi ₂ Se ₃ /MoSe ₂范德华异质结 (vdWH)，并使用第一性原理计算计算了异质结的电子和光学性质。还研究了外电场和层间距对异质结电子特性的影响。计算结果表明，固有的 Bi ₂ Se ₃ /MoSe ₂vdWH 具有 2 型带对齐，具有非常小的间接带隙 (28 meV)。它还具有很强的自旋-轨道耦合效应，同时观察到塞曼分裂和拉什巴分裂的特性。外加电场和改变层间距都可以有效调节异质结的能带结构；这些调制方式可以将vdWH的波段排列从type-2变为type-3甚至type-1，带隙类型可以由间接变为直接。异质结的红外吸收远高于Bi ₂ Se ₃和MoSe ₂。所有计算结果表明，Bi ₂ Se ₃ /MoSe ₂ vdWH 在光电和自旋电子器件方面具有良好的应用前景。