论文标题
高度调制的双重半导和半导
Highly Modulated Dual Semimetal and Semiconducting Gamma-GeSe with Strain Engineering
论文作者
论文摘要
分层的六边形伽玛（Game）是最近合成的GESE的新多晶型物，在单层（1L）的情况下，在半导体（1L）的情况下，以其大容量形式（甚至高于石墨）显示出惊人的电子电导率（甚至高于石墨）。 In this work, by using first-principles calculations, we demonstrate that, different from its orthorhombic phases of GeSe, the Gamma--GeSe shows a small spatial anisotropic dependence and a strikingly thickness-dependent behavior with transition from semimetal (bulk, 0.04 eV) to semiconductor (1L, 0.99 eV), and this dual conducting characteristic realized simply with thickness control in以前在其他2D材料中没有发现伽玛 - 基地。缺乏D轨道允许具有较小有效质量的电荷载体（电子为0.16 m0，孔为0.23 m0），可与磷烯相当。同时，1L伽玛 - gese的柔韧性具有较高的灵活性，Young的模量为86.59 N/m，仅占石墨烯和MOS2的四分之三，而Poisson的比例为0.26，表明具有高度柔韧的晶格。有趣的是，1L伽玛 - 基地显示出六角形对称性固有的平面各向同性弹性模量，而由于带边缘周围变化的山谷，各向异性的平面内有效质量。我们证明了应变工程在诱导间接区域和半导体 - 金属转变中的可行性，这是由于带边缘的竞争带带来的。我们的工作表明，游离的1L伽马 - 根 - 显示出强的光吸收（〜106 cm-1）和带有丰富山谷的间接带隙在带边缘，可以使高载流子浓度和较低的直接电孔重组速率较低，这对于纳米电子和溶质细胞的应用来说是有希望的。
Layered hexagonal Gamma--GeSe, a new polymorph of GeSe synthesized recently, shows strikingly high electronic conductivity in its bulk form (even higher than graphite) while semiconducting in the case of monolayer (1L). In this work, by using first-principles calculations, we demonstrate that, different from its orthorhombic phases of GeSe, the Gamma--GeSe shows a small spatial anisotropic dependence and a strikingly thickness-dependent behavior with transition from semimetal (bulk, 0.04 eV) to semiconductor (1L, 0.99 eV), and this dual conducting characteristic realized simply with thickness control in Gamma-GeSe has not been found in other 2D materials before. The lacking of d-orbital allows charge carrier with small effective mass (0.16 m0 for electron and 0.23 m0 for hole) which is comparable to phosphorene. Meanwhile, 1L Gamma--GeSe shows a superior flexibility with Young's modulus of 86.59 N/m, only one-quarter of that of graphene and three-quarters of that of MoS2, and Poisson's ratio of 0.26, suggesting a highly flexible lattice. Interestingly, 1L Gamma-GeSe shows an in-plane isotropic elastic modulus inherent with hexagonal symmetry while an anisotropic in-plane effective mass owing to shifted valleys around the band edges. We demonstrate the feasibility of strain engineering in inducing indirect-direct and semiconductor-metal transitions resulting from competing bands at the band edges. Our work shows that the free 1L Gamma-GeSe shows a strong light absorption (~106 cm-1) and an indirect bandgap with rich valleys at band edges, enabling high carrier concentration and a low rate of direct electron-hole recombination which would be promising for nanoelectronics and solar cell applications.
