MoSe_2电子结构和光学性质的理论研究

基于密度泛函理论第一性原理,计算了MoSe_2的能带结构、态密度和光学性质,再根据相关参数分析了该材料的半导体特性和光学性质。能带结构结果表明MoSe2具有间接带隙宽度为0.853 eV的半导体材料,从态密度图可看出价带由Mo的5s4d价电子和Se的4s4p价电子起主要作用,其它价电子作用较少导带主要是Mo的4d和Se的4s4p价电子作用。通过计算得到的复介电函数,根据其它光学参数与其之间的关系,分析获得复折射率、反射和吸收谱、能量损失函数和光电导率等光学性质。由光学性质可知复介电函数的峰值都出现在低能区;介于可见到紫外区域的光子具有最大的吸收系数2.99×10~5cm~(-1);在光子能量17.93 eV处,Mo的4s4d和Se的4p电子发生共振,其它区域能量损失值都趋于0,说明电子之间共振非常微弱。这些光学性质在制作微电子、光电子器件和紫外探测器方面有着广泛的应用前景。

THEORETICAL RESEARCH ON THE ELECTRIC STRUCTURE AND OPTICAL PROPERTIES OF MoSe2

Based on the first principle of DFT, the band structure, density of states and optical properties of MoSe₂ are calculated, and the semiconductor and optical properties of MoSe₂ are analyzed according to the relevant parameters. The analysis of band structure showed that MoSe₂ had a semiconductor material with an indirect band gap width of 0.853ev. Which could be seen that the valence band played a major role of the 5s4d valence electron of Mo and the 4s4p valence electron of Se through the density of state diagram, while the other valence electron was less conduction band, and the conduction band was mainly composed of the 4d valence electron of Mo and the 4s4p valence electron of Se. According to the relationship between other optical parameters and the calculated complex dielectric function, the optical properties such as complex refractive index, reflection and absorption spectrum, energy loss function and photoconductivity were obtained. It could be seen from the optical properties that the peak value of complex dielectric function appeared in the low-energy region. The photons in the visible ultraviolet region had the maximum absorption coefficient of 2.99×10⁵cm^-1. At the photon energy of 17.93eV, the 4s4d of Mo and 4p of Se had electron resonate, and the energy loss values in other regions tended to 0, the result indicated that the resonance was very weak between electrons. These optical properties had wide application prospects in the fabrication of microelectronics, optoelectronic devices and UV detectors.