Effects of different concentration S-doping on the structural stability and electronic structures of delafossite CuAlO₂

The sulphur concentration effects on the structural and electronic properties of S-doped CuAlO₂ have been investigated using the first-principles density functional theory. The calculated results show that the structural parameters increase with the doping concentration due to the S dopant. The obtained formation energies indicate that all S-doped CuAlO₂ with different concentrations are structural stability, but the stability decreases with the S doping concentration. Electronic structure calculations present that the band gap decreases with the increasing concentration due to the better hybridization between Cu-3d and S-3p states and the downward shift of Cu-3p states in conduction bands. The covalence of S-doped CuAlO₂ is enhanced and the localization is weakened, which are good for p-type conductivity.