二维锑烯电子结构与光学性质的第一性原理研究

Electronic structure and optical properties of two-dimensional antimony:A first principle study

二维锑烯具有石墨烯、BP、MoS2等典型二维材料相似的优越物理化学性质,在纳米光电子、生物医学等诸多领域展现了良好的应用前景,吸引了科学界的广泛关注.本文采用基于密度泛函理论的第一性原理方法,对少层锑烯的晶体结构、电子结构以及光学性能进行了系统研究.计算结果表明:随着层数增加,二维锑烯由半导体向导体过渡,材料的极化能力越来越强,静介电常数也越来越大,介电函数的虚部曲线随能量的变化,发生红移,峰值越来越大,锑烯的反射系数也越来越大.吸收曲线与介电函数虚部曲线相对应,随着层数的增加,也出现红移现象,对于长波段的光,层数越少,吸收越差,但对于紫外区域,均具有较好的吸收.这有助于我们全面地了解二维锑烯纳米片的物理性能,为其在光电材料和器件中的应用研究提供更多的理论依据.

Two-dimensional(2D) antimonene has similar physical and chemical properties as graphene, BP, MoS2 and other typical 2D materials. It has shown good application prospects in many fields such as nano-optoelectronics, biomedicine and attracted wide attention of the scientific community. In this paper, the crystal structure, electronic structure and optical properties of antimony with few-layers have been systematically studied by the first-principles method based on density functional theory. The results show that the bond lengths of antimonene in few-layers are shorter than those of bulk except monolayer, and the bond lengths and bond angles are smaller with the decrease of layers. In addition, with the increase of the number of layers, the antimonenes are transited from semiconductor to conductor, in which the monolayer is a semiconductor with indirect band-gap, the two and three layers are transitional states, and the four layers are completely transitional to metal state. This conclusion has been proven by PBE method, hybrid HSE06 method and van der Waal’s correction. It is also consistent with the results of density of states. The dielectric function analysis of the 2D antimonenes shows that, with the increase of layers, the polarization ability of antimonenes is stronger, and the static dielectric constant is larger. The imaginary part of dielectric function changes with the change of energy, and with the increase of the number of layers, the curve red-shifts and the frontal value increases. Overall, in the low and high energy regions of photons, with the increase of layer number, the reflection coefficient of antimonene is relatively larger, and in the middle region, the phenomenon of relative aggregation occurs. In addition, the absorption curve corresponds to the imaginary part curve of dielectric function. With the increase of the layer number, the red shift also occurs. For long wavelength light, the fewer number of layers, the worse absorption. But for the ultraviolet region, they all have good absorption. This conclusion is helpful for us to understand the physical and photoelectric properties of two-dimensional antimonene with few layers more comprehensively, and provides a good theoretical basis for the application and research of antimony photoelectric materials and devices.