论文标题
单层葡萄球菌缺陷的局部激子
Localized Excitons in Defective Monolayer Germanium Selenide
论文作者
论文摘要
葡萄球菌（GESE）是一种具有有希望的光电特性的范德华（Van der Waals）键入的分层材料，已针对2D半导体应用实验合成。在单层中，由于尺寸降低，因此，筛选环境，诸如缺陷的存在之类的扰动对其性质产生了重大影响。我们应用密度功能理论和多体扰动理论来了解包含$ -2 $电荷状态下单个硒空位的GESE的电子和光学特性。我们预测，空缺导致中间隙“陷阱状态”，该空缺强烈定位电子和孔密度，并导致尖锐，低能的光吸收峰在预测的原始光学间隙以下。对激子波功能的分析表明，原始单层的2D Wannier-mott激子围绕缺陷局部高度局部，将其BOHR半径降低了四倍，并且由于缺陷引起的对称对称性破裂而沿平面外轴产生了偶极矩。总体而言，这些结果表明，空缺是对系统的强烈扰动，表明在材料设计背景下考虑缺陷的重要性。
Germanium Selenide (GeSe) is a van der Waals-bonded layered material with promising optoelectronic properties, which has been experimentally synthesized for 2D semiconductor applications. In the monolayer, due to reduced dimensionality and, thus, screening environment, perturbations such as the presence of defects have a significant impact on its properties. We apply density functional theory and many-body perturbation theory to understand the electronic and optical properties of GeSe containing a single selenium vacancy in the $-2$ charge state. We predict that the vacancy results in mid-gap "trap states" that strongly localize the electron and hole density and lead to sharp, low-energy optical absorption peaks below the predicted pristine optical gap. Analysis of the exciton wavefunction reveals that the 2D Wannier-Mott exciton of the pristine monolayer is highly localized around the defect, reducing its Bohr radius by a factor of four and producing a dipole moment along the out-of-plane axis due to the defect-induced symmetry breaking. Overall, these results suggest that the vacancy is a strong perturbation to the system, demonstrating the importance of considering defects in the context of material design.
