First-principles study on the electronic and optical properties of two-dimensional graphene-like Zn1−xVxO (x = 0.0625, 0.125) monolayer

Abstract

In this paper, we used first principles with GGA + U to study the formation energy, electronic and optical properties of V-doped ZnO (Zn0.9375V0.0625O, Zn0.875V0.125O) monolayer with and without intrinsic vacancy. ZnO graphene-like monolayer has been synthesized recently and is a promising next generation nanodevices and optoelectronics. The unclear formation energy, properties are an obstacle in preparation, design, applications, which urgently need to clarify. The calculated formation energy shows V doping is easy to perform in an oxygen-rich atmosphere. Vanadium releases electrons to the monolayer system. A deep trapped level emerges in the band gap after V doping, which means V-doped ZnO monolayer with vacancy is defect sensitive. Oxygen vacancy is easier to form than zinc vacancy in practice. The relations between bands, optical properties and density of states were discussed. Oxygen vacancy tunes and shifts the absorption coefficient (α(ω)) to the visible and the solar energy region. Our studies can be used to explain the related experiments. We also can engineer the optical properties by introducing proper vacancy intentionally. Our paper not only paves a way for V-doped ZnO monolayer preparation, design and flexible applications in the future but also stimulates the related research.