Two-dimensional (2D) semiconductors with suitable direct band gaps, high carrier mobility, and excellent open-air stability are especially desirable for material applications. Herein, we show theoretical evidence of a new phase of a copper(I) sulfide (Cu₂S) monolayer, denoted δ-Cu₂S, with both novel electronic properties and superior oxidation resistance. We find that both monolayer and bilayer δ-Cu₂S have much lower formation energy than the known β-Cu₂S phase. Given that β-Cu₂S sheets have been recently synthesized in the laboratory (Adv. Mater.2016, 28, 8271), the higher stability of δ-Cu₂S than that of β-Cu₂S sheets suggests a high possibility of experimental realization of δ-Cu₂S. Stability analysis indicates that δ-Cu₂S is dynamically and thermally stable. Notably, δ-Cu₂S exhibits superior oxidation resistance, due to the high activation energy of 1.98 eV for the chemisorption of O₂ on δ-Cu₂S. On its electronic properties, δ-Cu₂S is a semiconductor with a modest direct band gap (1.26 eV) and an ultrahigh electron mobility of up to 6880 cm² V⁻¹ s⁻¹, about 27 times that (246 cm² V⁻¹ s⁻¹) of the β-Cu₂S bilayer. The marked difference between the electron and hole mobilities of δ-Cu₂S suggests easy separation of electrons and holes for solar energy conversion. Combination of these novel properties makes δ-Cu₂S a promising 2D material for future applications in electronics and optoelectronics with high thermal and chemical stability.

中文翻译：

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硫化 铜（i）：具有优异的抗氧化性和高载流子迁移率的二维半导体†

具有合适的直接带隙，高载流子迁移率和出色的露天稳定性的二维（2D）半导体特别适合材料应用。这里，我们示出了铜（一个新的阶段的理论依据我）硫醚（CU ₂ S）单层，表示为δ-Cu系₂ S，既新颖的电子性能和优良的抗氧化性。我们发现，单层和双层δ铜₂ ■找比已知的β铜低得多的地层能量₂ S期。鉴于β-Cu系₂小号床单的实验室（最近合成进阶母校。2016，28，8271），δ-Cu的更高的稳定性₂比那β-Cu构成_2个小号片表明实验实现δ-Cu构成的高可能性₂ S.稳定性分析表明，δ-Cu系₂小号动态和热是稳定的。值得注意的是，δ-Cu系₂小号表现出优良的抗氧化性，由于对的O-化学吸附1.98电子伏特的高活化能₂上δ铜₂ S.在其电子特性，δ-Cu系₂ S是具有适中的半导体直接带隙（1.26电子伏特）和最多至6880厘米超高电子迁移率² V ^-1小号^-1，约27倍（246厘米² V ^-1小号^-1）的β-的Cu ₂S双层。δ-Cu的电子和空穴迁移率之间的显着差异₂小号提出了太阳能转换的电子和空穴的容易分离。这些新颖的特性品牌δ铜的组合₂ S A有为2D材料在电子和光电子具有高热和化学稳定性未来的应用。