Abstract

Utilizing first-principles calculations, we have investigated the structural, electronic, and optic properties of a series of two-dimensional (2D) stable direct band-gap semiconductors, which are M₂XY (M = Ga, In; X,Y = S, Se, Te) in group-III-V with the Janus single layer structures. Meanwhile, the MX (M = Ga, In; X = S, Se, Te) of binary single layer structures, which are parent materials for Janus structures, have also been investigated. The electronic structures are calculated via GW₀ self-consistency, and the results show that these Janus monolayer structures belong to the direct band-gap semiconductors with large band gap. In contrast to the indirect band-gap MX monolayers, it indicates that an indirect-direct band-gap transition can be realized by constructing Janus structures. Moreover, we systematically investigated the optic response properties of M₂XY Janus single layers by solving the Bethe-Salpeter equation (BSE), and the exciton absorption peaks are observed in these monolayer structures. Our results show that these Janus structure materials should be potential candidates for optoelectronic nanodevices.

Graphical abstract

中文翻译：

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基于GW和Bethe-Salpeter方程的一系列M 2 XY（M = Ga，In; X，Y = S，Se，Te）Janus单层材料的结构，电子和光学性质

摘要

利用第一性原理计算，我们研究了一系列二维（2D）稳定直接带隙半导体的结构，电子和光学性质，它们是M ₂ XY（M = Ga，In; X，Y = S，Se，Te）在III-V组中，具有Janus单层结构。同时，还研究了作为Janus结构母体的二元单层结构MX（M = Ga，In; X = S，Se，Te）。通过GW ₀计算电子结构结果表明，这些Janus单层结构属于带隙较大的直接带隙半导体。与间接带隙MX单层相反，它表明可以通过构建Janus结构来实现间接-直接带隙跃迁。此外，我们通过求解Bethe-Salpeter方程（BSE），系统地研究了M ₂ XY Janus单层的光学响应特性，并且在这些单层结构中观察到了激子吸收峰。我们的结果表明，这些Janus结构材料应该是光电纳米器件的潜在候选者。

图形概要