新型二维SeC₂O半导体及其光电性质

New Two-Dimensional SeC₂O Semiconductor and Its Optoelectronic Properties

摘要: 探索具有独特结构和性质的新型三元二维材料是当前的研究热点，因其是研究高性能器件的理想候选材料。本文基于密度泛函理论，从理论上预测了一种新型三元二维SeC₂O晶体。其优异的稳定性已从热力学、力学、分子动力学及高温环境等多方面得到验证。该晶体被证实为带隙2.79 eV的间接带隙半导体。在外加双轴应力(−20%~+20%)作用下，其电子能带结构呈现丰富变化，例如带隙在1.60至3.27 eV间连续变化。随后研究了氢化对其电子能带结构的影响：通过三种氢化方案(包括一种完全氢化和两种半氢化)获得的二维SeC₂O晶体带隙值分别为4.10 eV、2.63 eV和3.33 eV。值得关注的是，在三种氢化结构中，有两种结构表现出良好的动力学稳定性，其中一种半氢化二维SeC₂O晶体被证实为直接带隙半导体。最后对纯相及氢化二维SeC₂O晶体的光学特性进行了研究分析。本研究结果揭示了二维SeC₂O晶体在蓝光波段光电探测器方面具有应用前景。

Abstract: Discovering new ternary two-dimensional (2D) materials with unique structure and properties is a hot research topic, for it is a good candidate for investigating high-performance devices. In this paper, a new ternary 2D SeC₂O crystal was theoretically predicted based on density functional theory. Its excellent stability has been verified from multiple aspects, that is, from thermodynamics, mechanics, molecular dynamics, and high-temperature environments. It is found to be an indirect semiconductor with a band gap of 2.79 eV. Under the action of applied biaxial strain (−20%~+20%), its electronic band structure exhibits rich variations. For example, the band gap changes continuously from 1.60 to 3.27 eV. Next, the effect of hydrogenation on its electronic band structure was investigated. The band gap values of the 2D SeC₂O crystals obtained from three hydrogenation schemes (including one full hydrogenation and two semi-hydrogenation) are 4.10, 2.63, and 3.33 eV, respectively. Excitingly, it is found that among the three hydrogenated structures of the 2D SeC₂O crystals, two structures have good kinetic stability, and one semi-hydrogenated 2D SeC₂O crystal is found to be a direct band gap semiconductor. Finally, the optical properties of pure and hydrogenated 2D SeC₂O crystals were studied and analyzed. Our results indicate that the 2D SeC₂O crystals have application prospects in the field of blue light photodetectors.