Ca掺杂SnS2电子结构和光学性质的第一性原理研究

First-Principles Study of Electronic Structure and Optical Properties of Ca-Doped SnS2

本论文采用基于密度泛函理论的第一性原理计算方法,研究了Ca掺杂SnS2材料的电子结构和光吸收性质。计算结果表明,采用optB86b + vdWDF交换关联泛函计算得到的晶格结构与实验结果符合的很好,说明包含范德瓦尔斯作用的vdW-DF泛函,能够更好的描述层状SnS2材料的物理性质。态密度分析表明,Ca掺杂在费米能级之上引入了未占据的杂质态,材料表现为p型半导体。光吸收性质的计算结果表明,掺杂后体系在带边附近吸收系数大于未掺杂体系,表明采用低价金属Ca掺杂的方法,能够有效提高SnS2材料在可见光区的光吸收能力,以上结果为层状SnS2材料在光电领域的应用提供可靠的理论基础。

The electronic structure and optical properties of Ca-doped SnS2 were investigated by first princi-ples calculations based on density functional theory. The structural properties calculated with the optB86b + vdWDF functional are in good agreement with experimental results. Thus, consideration of the vdW interactions is important for theoretical investigation of SnS2. For Ca doped single-layer SnS2, the occurrence of unoccupied defect states, located above the valence band maximum, indicates p-type doping for Ca doped SnS2. The calculated optical absorption spectra show that absorption edges of the doped systems exhibit red shift with respect to pure SnS2. It indicates that low valence metal Ca doping is beneficial to improve the optical absorption in the visible light range. The above results can provide reliable guidance for its experimental application in optoelectronics.