The effect of biaxial strain on the optoelectronic properties of a single-layer 2H-GaS system with S vacancies

In this paper, density functional theory (DFT) is used to systematically study the S-vacancy defect system in a single layer of 2H-GaS and the effects of biaxial tensile and compressive strains on the geometric structure, electronic structure, and optical properties of this defect system are discussed. The study's results show that different defect atoms can influence the formation of defect systems, among which S-vacancy defects show high stability.Under biaxial tensile strain, the band gap of GaS shows a significant reduction under compressive strain,it tends to decrease and then increase. Optical property analysis shows that tensile strain causes a blue shift in the defective system's ultraviolet (UV) reflectivity and absorption coefficient, while compressive strain significantly increases these coefficients. The above results provide a theoretical basis for applying GaS-based materials in sensors, flexible electronics, and optoelectronic devices.