Manganese doping and optical properties of ZnS nanoribbons by postannealing

Manganese (Mn) doping of ZnS nanoribbons was achieved by simple thermal annealing. Upon heating ZnS nanoribbons with MnS powder up to 700 °C, the intrinsic photoluminescence (PL) of the annealed nanoribbons disappeared and a new PL peak at 585 nm gradually emerged. Significantly, the annealing process induced no detectable change in the morphology and uniform hexagonal wurtzite 2H structure of the single-crystal ZnS nanoribbons. The PL peak at 585 nm is attributed to Mn dopant and confirms Mn incorporation in ZnS because (1) the peak appears only when ZnS ribbons were annealed with MnS, but does not appear without MnS, (2) its intensity increases with increasing annealing temperature, which is consistent with increased incorporation of Mn²⁺ ions, and (3) its position is similar to that of Mn-related emission in ZnS, and is independent of the measuring temperature and excitation power. This work demonstrates the capability of doping nanostructured materials by simple postannealing treatment.