Ce、Ga、La掺杂二维SnO2电子结构及光电性质的第一性原理研究

二维材料具有优异的光学、力学、热学、磁学等性质，成为研究的热点之一. SnO₂薄膜中的电子迁移率非常高，兼具透明和良好的导电性能，是一种性能绝佳的半导体材料.本文用密度泛函理论框架下的第一性原理研究了二维SnO₂及其掺杂体系的电子结构、电子态密度、导电性能及光学性质，计算结果表明：相比较于三维SnO₂,二维SnO₂的费米能级附近产生很多杂质能级，提高了载流子浓度，带隙明显变窄，电子的局域性增强，导带中电子的有效质量增加了，电子跃迁更容易发生，增加了材料的导电性能；二维SnO₂比三维SnO₂材料的电极化能力强，在红外区、可见光区、紫外区域的光子吸收性能更优异，光电导率更高，更有利于光生电子-空穴对的分离和迁移，即可以有效地提高其光电转换效率，其中掺杂La元素能更好地提高在红外区、可见光区及紫外区吸收光子的能力，更有利于光电转换的效率，提高导电性.

First-principles study on electronic structure and photoelectric properties of Ce, Ga and La doped two-dimensional SnO2

Two-dimensional materials become one of the research hotspots due to the excellent optical, mechanical, thermal and magnetic properties. SnO2 film is a kind of excellent semiconductor material with high electron mobility, good conductivity and transparency. In this paper, the electronic structure, electronic state density, electrical conductivity and optical properties of pure and doped SnO2 have been studied using the first principles of density functional theory. The calculation results show that a lot of impurity levels are generated near the Fermi level of two-dimensional SnO2 compared with three-dimensional SnO2, which improves the carrier concentration, narrates the band gap, enhances the localization of electrons, increases the effective mass of electrons in the conduction band, and facilitates the occurrence of electronic transitions, thus increasing the conductivity of materials. Two-dimensional SnO2 material has stronger electrical polarization ability than three-dimensional SnO2 material, and has better photon absorption performance and higher photoconductivity in infrared, visible and ultraviolet regionregions, which is more favorable for the separation and migration of photoelectron-hole pairs, that is, it can effectively improve its photoelectric conversion efficiency. Secondly, doping La can better improve the ability of absorbing photons in infrared, visible and ultraviolet regions, which is more conducive to the efficiency of photoelectric conversion and improve the conductivity.