Alloying in two-dimensional (2D) transition metal dichalcogenides (TMDCs) has allowed band gap engineering and phase transformation, as well as modulation of electronic properties. However, most of the efforts have been focused on alloying between transition metal cations. Among those that emphasize alloying between chalcogenide anions, the sulfide–selenide combinations are popular with a few reports on selenide–telluride combinations. In this work, we show a facile chemical vapor deposition method to obtain stable alloying between selenide and telluride anions in monolayer MoSe_2(1–x)Te_2x alloy. These alloys retain the monolayer 2H symmetry and show good photoluminescence and band gap tunability in the near-infrared region. The nature and percentage of alloying is further confirmed and quantified via AFM, XPS, and HAADF-STEM imaging and polarized Raman spectroscopy. The stability of the two chalcogens in the monolayer 2H lattice is also consistent with thermodynamic phase mixing via DFT simulations. The work demonstrates a straightforward method of synthesizing telluride-based 2D TMDC alloys for further studies and emerging applications.

中文翻译：

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二元二维过渡金属双硫属化物合金的碲化物基原子薄层。

二维（2D）过渡金属二卤化金属（TMDC）的合金化已实现了带隙工程设计和相变以及电子性能的调节。但是，大多数努力都集中在过渡金属阳离子之间的合金化上。在那些强调硫族化物阴离子之间形成合金的反应中，硫化物-硒化物组合很受欢迎，有关硒化物-碲化物组合的报道也很少。在这项工作中，我们展示了一种简便的化学气相沉积方法，可在单层MoSe _{2（1- x）} Te _{2 x中}获得硒化物和碲化物阴离子之间的稳定合金化合金。这些合金保持单层2H对称性，并在近红外区域显示出良好的光致发光和带隙可调性。通过AFM，XPS和HAADF-STEM成像以及偏振拉曼光谱进一步确认并量化了合金化的性质和百分比。通过DFT模拟，单层2H晶格中两种硫属元素的稳定性也与热力学相混合相一致。这项工作展示了一种直接合成基于碲化物的2D TMDC合金的简单方法，可用于进一步的研究和新兴的应用。