Ge-vacancy improved the optical and electronic properties of GeAs2 semiconductor.

GeAs 2 is an attractive semiconductor. However, the structure, optical properties and electronic properties of GeAs 2 with Ge-vacancy are unclear. Here, we use the first-principles to investigate the effect of Ge-vacancy on the structure, optical and electronic properties of GeAs 2. Two Ge vacancies are considered here. The results show that V –Ge1 -vacancy is more thermodynamically stable than that of V –Ge2 -vacancy because the bond strength of Ge–As bond for V –Ge1 -vacancy is stronger than that of the V –Ge2 -vacancy. GeAs 2 shows the ultraviolet behavior. In particular, those Ge-vacancies decrease the optical absorption coefficient of GeAs 2. The calculated band gap of GeAs 2 is 0.574eV, indicating that GeAs 2 is a semiconducting. GeAs 2 with those Ge vacancies show metallic behavior because Ge-vacancies promote the electronic transfer near the E F. [ABSTRACT FROM AUTHOR]