A study of the electrical and optical properties of Cr2+: ZnSe nano-sheets by first-principle calculations

The electronical and optical properties of Cr2+: ZnSe nano-sheets have been investigated by first-principle calculations on the basis of density functional theory. Cr2+ ions doping make Cr2+: ZnSe nano-sheets become magnetic and the magnetic moment is 4. Impurity bands mainly composed of Cr(d) electrons are introduced in the bandgap. New absorption peaks are observed at 0.8 eV in all Cr2+: ZnSe nano-sheets, which is quite stable and does not move with the varying of the layer number. But the intensity of the absorption peaks increases with the decreasing of the layer number, which is attributed to the increasing of Cr2+ ion concentration. The electron transitions from dxz and dx2-y2 orbital to dz2, dxy, and dyz orbital are thought to be the cause for the new absorption peaks.