基于密度泛函理论下O和Na掺杂单层h-BN的电子结构性质和光学效应的分析

基于密度泛函理论的第一性原理方法研究了O、Na单掺杂及O和Na共掺杂单层h-BN的形成能、电子结构和光学性质.结果表明:单掺杂体系中，O掺杂N位置、Na掺杂B位置时，掺杂形成能最低;共掺杂体系中，O和Na邻位掺杂，掺杂形成能最低.与单层h-BN相比，引入杂质原子后的体系禁带宽度均减小，其中O掺杂为n型掺杂，Na掺杂为p型掺杂，而O和Na共掺h-BN体系为直接带隙材料，有利于提高载流子的迁移率.在光学性质方面，Na掺杂h-BN体系与O和Na共掺h-BN的静介电常数均增大，在低能区介电虚部和光吸收峰均发生红移，其中Na掺杂体系红移最为显著，极化能力最强.因此Na单掺和O和Na共掺有望增强单层h-BN的光催化能力，可扩展其在催化材料、光电器件等领域的应用.

Analysis of electronic structure properties and optical effects of O and Na doped monolayer h-BN based on density functional theory

The formation energy, electronic structure and optical effects of O and Na single doped and O-Na co-doped monolayer h-BN are studied by using the first-principles method based on density functional theory.The results show that the doping formation energy is the lowest when O is doped at N position and Na is doped at B position; In the co-doped system, O and Na are ortho-doped, and the doping formation energy is the lowest. Compared with monolayer h-BN, the band gap width of the system is reduced after introducing impurity atoms, in which O doping is n-type doping, Na doping is p-type doping, and O-Na co-doped h-BN system is a direct band gap material, which is beneficial to improve carrier mobility. In terms of optical properties, the static dielectric constant of Na doped h-BN system and O and Na co-doped h-BN increase, and the imaginary part of dielectric and optical absorption peak in the low energy region are red-shifted. Among them, the Na doped system has the most significant redshift and the strongest polarization ability. Therefore, Na monodoping and O and Na co-doping are expected to enhance the photocatalytic ability of monolayer h-BN and expand its application in photocatalysis materials, optoelectronic devices and other fields.