Preparation of ZnSe powder by vapor reaction during combustion synthesis

ZnSe powders have been prepared by vapor reaction during combustion synthesis. The powders contain both cubic and hexagonal ZnSe, where the fraction of the hexagonal phase increases with increasing distance from the evaporation source. The powders consist of spherical particles and rod-like crystals with sizes from submicron to a few microns. In UV-Vis region, the ZnSe powders have two absorption edges at 450-500 nm and 650-700 nm, likely connected with intrinsic band-gap transition and defect energy levels. From the optical absorption data, the band-gap of the ZnSe powders is estimated to be 2.4-2.5 eV. Under an UV or blue excitation, the ZnSe powders show very weak near-band-edge emission but strong defect-induced red emission. It appears that the ZnSe powders synthesized by vapor reaction clearly differ from the bulk ZnSe sample by melt solidification in both phase composition and optical properties.