First Principles Study on the Two-dimensional Germanium Arsenide Containing Vacancy

摘要

Two-dimensional layered materials exhibit exotic optical, electrical and thermoelectric properties, which have drawn worldwide attention in the past decade. As a novel kind of two-dimensional semiconductor, monolayer Germanium Arsenide (GeAs) can be exfoliated from bulk solid and it owns excellent dynamical and thermal stability and tunable bandgap. Based on the first principles calculations, we investigate the geometric structure, electrical and magnetic properties of the pristine, Germanium vacancy (V_(Ge)) defected and Arsenide vacancy (V_(As)) defected monolayer GeAs. In agreement with the experimental results, the pristine monolayer GeAs is a direct bandgap semiconductor with a forbidden band width of 1.48eV. By applying a full spin-polarized description to the system, we find that pristine monolayer GeAs is non-magnetic. Introduction of an atomic vacancy defect in the unit cell of monolayer GeAs can lead to six unequal structures. The most stable structure of monolayer GeAs with V_(Ge) is also a direct bandgap semiconductor with a forbidden band width of 0.17eV and is non-magnetic. The most stable structure of monolayer GeAs with V_(As) can generate a magnetic moment of 0.4μ_B, and it has desired half-metallic behavior. These intriguing results indicate that both pristine and intrinsic vacancy defected monolayer GeAs are promising candidates for two-dimensional optoelectronics and spintronic devices with high performance.