二维GaAs电子结构和光学性质的理论计算

Theoretical Calculation of Electronic Structure and Optical Properties of Two-Dimensional GaAs

采用基于密度泛函理论的第一性原理和分子动力学理论,验证了二维GaAs类石墨烯结构的稳定性,计算了二维GaAs的基态电子结构、态密度和光学性质参数。结果表明,不同于三维GaAs,二维GaAs最高的两个能带相互交叠,显示出金属性;维度的降低使得As的s态和p态电子相互作用增强,产生较多的态密度峰,且峰位向低能方向移动;低能带主要由Ga-d态、As-s态和As-p态构成;高能带主要由As-s态和As-p态构成;二维GaAs静态介电常数为3.67,对紫外光具有较强的吸收作用,在光子能量3.90~4.71eV和5.69~6.90eV范围表现出金属反射特性。

The stability of two-dimensional （2D） graphene-like GaAs is theoretically verified by the first-principles method based on the density functional theory （DFT） and the molecular dynamics （MD）. The energy band structure, density of states （DOS）, and parameters for describing optical properties of 2D GaAs are calculated. The results show that, two-dimensional GaAs is different from three-dimensional GaAs, and it shows a metallic property because the two highest bands are overlapping. The dimension reduction results in the enhancement of the interaction among electrons in s and d states of As. More DOS peaks occur with peak position shifts towards a low energy direction. The lower energy bands are composed of Ga-d, As-s and As-p states, and the higher energy bands are composed of As-s and As-p states. The 2D GaAs has a static permittivity of 3.67, and has a strong absorption for ultraviolet light. It shows a metallic reflection characteristic in the photon energy ranges of 3.90-4.71 eV and 5.69-6.90 eV.