First-priniciple study of electrical and optical properties of (Al,Sn) co-doped ZnO

Abstract

The electrical and optical properties of Al–Sn co-doped ZnO have been investigated using density functional theory based on first-principles ultrasoft pseudopotential method. Firstly, Ef decrease indicates that Al–Sn codoping is easier to implement than Al mono-doping. Secondly, the splitting energies between HHB and CSB of ZnO:Al–Sn become more greater than that of ZnO:Al, while the splitting energies between LHB and HHB of pure ZnO, ZnO:Al and ZnO:Al–Sn are almost no altering. Meanwhile, Al mono-doping and Al–Sn codoping have smaller electron and hole effective masses than pure ZnO. In addition, for ZnO:Al–Sn, a new peak of imaginary part of dielectric function located at about 1.2eV, and the number of dielectric peaks decreases. The reflectivity and absorptivity of ZnO:Al–Sn are larger than pure ZnO, indicating that the average optical transmittance in visible range significantly reduced, which is in agreement with the experimental result.