The properties of six kinds of intrinsic point defects in monolayer GeS are systematically investigated using the “transfer to real state” model, based on density functional theory. We find that Ge vacancy is the dominant intrinsic acceptor defect, due to its shallow acceptor transition energy level and lowest formation energy, which is primarily responsible for the intrinsic p-type conductivity of monolayer GeS, and effectively explains the native p-type conductivity of GeS observed in experiment. The shallow acceptor transition level derives from the local structural distortion induced by Coulomb repulsion between the charged vacancy center and its surrounding anions. Furthermore, with respect to growth conditions, Ge vacancies will be compensated by fewer n-type intrinsic defects under Ge-poor growth conditions. Our results have established the physical origin of the intrinsic p-type conductivity in monolayer GeS, as well as expanding the understanding of defect properties in low-dimensional semiconductor materials.

基于密度泛函理论，使用“转移到真实状态”模型系统地研究了单层GeS中六种本征点缺陷的性质。我们发现 Ge 空位是主要的本征受体缺陷，由于其浅的受体跃迁能级和最低的形成能，这主要负责单层 GeS 的本征 p 型导电性，并有效地解释了本征 p 型导电性实验中观察到的 GeS。浅受体跃迁水平源于带电空位中心与其周围阴离子之间的库仑排斥引起的局部结构变形。此外，就生长条件而言，Ge空位将通过在Ge贫乏的生长条件下较少的n型本征缺陷来补偿。