Electronic Structures and Optical Properties of Cu:MgF2 Crystal

Based on the density functional pseudopotential method, the geometries, electronic structures, and optical properties of MgF2 with different atomic fractions of Cu doping (2.08%, 4.16%, and 6.24%) are compared in detail. Cu substitution of the Mg sites induces an effective reduction of the band gap of MgF2; and the band gap is continuously reduced with increasing Cu doping level. Also, the calculations show that the refractive index and absorption increase with increasing Cu doping. More importantly, an absorption around 4 eV is found. The mechanisms of this transition in the doped and undoped materials are discussed. The Cu doped MgF2 system could be a potential candidate for photoelectrochemical applications.