Electronic structures, magnetic properties, half-metallicity and optical properties of the zincblende Zn1−xMoxS

Abstract The electronic structures, magnetic properties, half-metallicity and optical properties of Zn 1 - x Mo x S ( x =0.00, 0.25, 0.50, 0.75, 1.00) are studied by spin-polarized first-principles calculation. Excepting the Zn 0.5 Mo 0.5 S system with a tetragonal structure, the other systems Zn 1 - x Mo x S ( x =0.00, 0.25, 0.75, 1.00) are all in the cubic structure. The lattice constants (volumes) of the Mo doped systems are larger than those of the pure ZnS due to the atomic radius of 2.01 A for Mo atom larger than that of 1.53 A for Zn atom. Although pure ZnS is a nonmagnetic semiconductor with a wide band gap of 3.12 eV, due to incompletely filled Mo-4d orbital both the moderate Mo doped systems Zn 0.5 Mo 0.5 S and Zn 0.25 Mo 0.75 S are magnetic metal, especially the less Mo doped system Zn 0.75 Mo 0.25 S and the completely Mo doped system MoS are magnetic half-metal. For Zn 0.75 Mo 0.25 S system with a magnetic half-metal character as one example, the conducted spin-up channel is only contributed by the threefold degenerate t 2g ( d x y , d y z , d z x ) states due to the tetrahedral crystal field of the S atoms pushing the spin-up channel of the double degenerate e g ( d z 2 , d x 2 - y 2 ) states down below the Fermi level E F . Mo doping not only influences the shape of the original broad absorption peak ranging from 2.5 to 20 eV of pure ZnS, but also leads to two new narrow absorption peaks appeared in the ranges from 0 to 3 eV and from 33 to 43 eV. Moreover, their maximum absorption rate and the corresponding energy increase with increasing Mo content. These results are very useful for Zn 1 - x Mo x S to be applied in optical detectors and spintronics devices.