Cu掺杂MgF_2晶体的电子结构及光学特性

Electronic Structures and Optical Properties of Cu:MgF_2 Crystal

基于密度泛函理论(DFT)的第一性原理平面波超软赝势方法,计算了纯的MgF2晶体和掺杂不同原子分数(2.08%,4.16%,6.24%)Cu的MgF2晶体结构、电学性质以及光学性质.结果表明:Cu的掺入导致MgF2晶体禁带宽度逐渐变窄,并且Cu掺杂使得MgF2晶体折射率和吸收峰增加,特别是在4eV附近区域出现了新吸收峰.同时也给出了引起体系性质变化的物理机制,Cu掺杂MgF2晶体在光电化学方面有着潜在的应用价值.

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.