Cl掺杂Cu_2O的第一性原理计算

First Principles Calculation of Cl Doped Cu_2O

为了探究Cl杂质对Cu_2O体系的影响机理,采用基于密度泛函理论的第一性原理,通过Cl原子代替O原子建立同等条件下不同浓度的Cu_2O1-xClx模型,并对Cu_2O的晶体结构进行优化,计算并分析体系的几何结构、能带结构、态密度和光学特性。计算结果表明:Cl掺杂导致Cu_2O的晶格常数变大,并在Cu_2O禁带中形成了一条主要由Cl 3p轨道组成的浅施主杂质能级。该能级跨越费米面,使电子可以经过杂质能级跃迁至导带,减少了电子跃迁所需要的能量,使Cu_2O呈现半金属性;随着掺杂浓度的增大,禁带宽度依次减小为0.444,0.424,0.221 eV,从而出现吸收带边的红移;不同浓度Cl掺杂下,Cu_2O对可见光的吸收能力得到极大改善。

In order to explore the influence mechanism of Cl impurities on Cu2O system,by using the first principles based on the density function theory,the Cu2O1-xClx models with different Cl concentrations were established through replacing O atoms with Cl atoms under the same condition,and the crystal structure of Cu2O was optimized.The geometry structure,band structure,density of states and optical properties of the system were calculated and analyzed.The calculation results indicate that due to the Cl doping,the lattice constant of Cu2O is increased,and a shallow donor impurity energy level mainly composed of Cl 3p orbitals is formed in the Cu2O forbidden band.The energy level crosses the Fermi level,so the electrons can easily transit from the impurity level to the conduction band,the energy for the electron transition decreases,and the doped Cu2O exhibits a characteristic of semimetal.With the increase of the doping concentration,the forbidden bandwidths decrease to 0.444,0.424 and 0.221 eV,respectively,which results in the absorption band edge red-shift of Cu2O.Through the Cl doping with different concentrations,the absorption ability of Cu2O to the visible light is greatly enhanced.