Intrinsic point defects in pristine and Zn-doped GaAs nanowire surfaces: A first-principles investigation

Abstract Utilizing first-principles calculations, we have systematically investigated on the impact of surface point defects on the stability, electronic and optical properties of pristine and Zn-doped GaAs nanowires. Different defect types (antisite, interstitial and vacancy defect) and defect sites (surface, subsurface and core layer of nanowires) are considered to build defect models. Results show that AsGa and GaAs are respectively the most stable surface defect under As-rich condition and under Ga-rich condition, in both pristine and Zn-doped GaAs nanowires. Compared with the pristine model, Zn-doped GaAs nanowire will suffer a more significant surface defects under the same growth conditions due to lower formation energy. In addition, the band structure and electron density difference calculations indicate that GaAs, Asin and VGa act as acceptors, while AsGa, Gain and VAs act as donors. Interestingly, the incorporation of AsGa defect will notably weaken the p-type character of Zn-doped GaAs nanowires. Moreover, the optical absorption capability of pristine and Zn-doped GaAs nanowires will be subject to varying degrees of variation after introducing different defects.