Guo Yu, Wu Qisheng, Li Yunhai, Lu Ning, Mao Keke, Bai Yizhen, Zhao Jijun, Wang Jinlan, Zeng Xiao Cheng
Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian, Liaoning 116024, China.
Nanoscale Horiz. 2019 Jan 1;4(1):223-230. doi: 10.1039/c8nh00216a. Epub 2018 Sep 27.
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 (CuS) monolayer, denoted δ-CuS, with both novel electronic properties and superior oxidation resistance. We find that both monolayer and bilayer δ-CuS have much lower formation energy than the known β-CuS phase. Given that β-CuS sheets have been recently synthesized in the laboratory (Adv. Mater.2016, 28, 8271), the higher stability of δ-CuS than that of β-CuS sheets suggests a high possibility of experimental realization of δ-CuS. Stability analysis indicates that δ-CuS is dynamically and thermally stable. Notably, δ-CuS exhibits superior oxidation resistance, due to the high activation energy of 1.98 eV for the chemisorption of O on δ-CuS. On its electronic properties, δ-CuS is a semiconductor with a modest direct band gap (1.26 eV) and an ultrahigh electron mobility of up to 6880 cm V s, about 27 times that (246 cm V s) of the β-CuS bilayer. The marked difference between the electron and hole mobilities of δ-CuS suggests easy separation of electrons and holes for solar energy conversion. Combination of these novel properties makes δ-CuS a promising 2D material for future applications in electronics and optoelectronics with high thermal and chemical stability.
具有合适的直接带隙、高载流子迁移率和优异的露天稳定性的二维（2D）半导体对于材料应用尤为理想。在此，我们展示了一种硫化亚铜（CuS）单层新相（表示为δ-CuS）的理论证据，它具有新颖的电子特性和卓越的抗氧化性。我们发现，单层和双层δ-CuS的形成能都比已知的β-CuS相低得多。鉴于β-CuS片材最近已在实验室中合成（《先进材料》，2016年，第28卷，8271页），δ-CuS比β-CuS片材更高的稳定性表明δ-CuS具有很高的实验实现可能性。稳定性分析表明，δ-CuS在动力学和热学上都是稳定的。值得注意的是，δ-CuS表现出卓越的抗氧化性，这是由于O在δ-CuS上化学吸附的活化能高达1.98 eV。关于其电子特性，δ-CuS是一种半导体，具有适度的直接带隙（1.26 eV）和高达6880 cm² V⁻¹ s⁻¹的超高电子迁移率，约为β-CuS双层（246 cm² V⁻¹ s⁻¹）的27倍。δ-CuS电子和空穴迁移率之间的显著差异表明电子和空穴易于分离，有利于太阳能转换。这些新颖特性的结合使δ-CuS成为一种有前途的二维材料，有望在具有高热稳定性和化学稳定性的电子学和光电子学领域得到未来应用。
