发表机构
University of Rajshahi（拉杰沙希大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过第一性原理计算，揭示了Janus CrSiCN4和CrGeCN4单层的谷电子学、压电及光催化特性，表明组分和应变可调控其性能，为多功能纳米器件设计提供了依据。
AI 中文摘要
二维Janus半导体整合了自旋-谷耦合、压电性和可调光学响应，为多功能纳米器件提供了平台。本文通过第一性原理计算揭示了CrSiCN4和CrGeCN4单层中互补的组分与应变效应。两者均为非磁性直接带隙半导体，采用包含自旋轨道耦合的Perdew-Burke-Ernzerhof泛函计算得到的带隙分别为1.23 eV和1.09 eV；HSE06杂化泛函计算保留了直接带隙特性，对应带隙为CrSiCN4的1.46 eV和CrGeCN4的1.19 eV。在K和K'点出现相反的面外自旋特征和Berry曲率。双轴应变将两者的带隙分别从1.59 eV降至0.86 eV、从1.44 eV降至0.63 eV，驱动直接带隙向间接带隙转变，使吸收光谱红移，同时保留谷自旋对比度。CrGeCN4表现出更大的面内压电响应，而CrSiCN4的面外压电响应幅度更大。带边排列满足氧析出反应的要求，但为氢析出反应提供的驱动力不足，这为后续通过应变诱导的带边调制实现全解水提供了动机。这些结果确立了组分和应变作为互补调控手段，可用于定制Cr基Janus单层，以应用于谷电子学、光电子学、机电学和光催化领域。
英文摘要
Two dimensional Janus semiconductors integrating spin-valley coupling, piezoelectricity, and tunable optical responses offer a platform for multifunctional nanodevices. Here, first-principles calculations reveal complementary composition and strain effects in CrSiCN4 and CrGeCN4 monolayers. Both are found to be nonmagnetic direct-gap semiconductors, with gaps of 1.23 and 1.09 eV using the Perdew-Burke-Ernzerhof functional including spin-orbit coupling, respectively. HSE06 hybrid-functional calculations retain the direct-gap character, yielding gaps of 1.46 eV for CrSiCN4 and 1.19 eV for CrGeCN4. Opposite out-of-plane spin character and Berry curvature emerge at K and K'. Biaxial strain reduces the respective gaps from 1.59 to 0.86 eV and 1.44 to 0.63 eV, drives direct-to-indirect transitions, and redshifts absorption while preserving valley spin contrast. CrGeCN4 exhibits larger in-plane piezoelectric response, whereas CrSiCN4 exhibits larger out-of-plane magnitude. Band-edge alignment satisfies the oxygen evolution reaction requirement but provides insufficient driving force for the hydrogen evolution reaction, motivating further strain-induced band-edge modulation toward overall water splitting. These results establish composition and strain as complementary controls for tailoring Cr-based Janus monolayers for valleytronic, optoelectronic, electromechanical, and photocatalytic applications.
