表面修饰调控单层ZnS电子结构和光学性质

Electronic structures and optical properties of the surface regulated two-dimensional ZnS

摘要:

为了研究H, F修饰单层ZnS对其电子结构和光学性质的影响，建立了H修饰、F修饰以及H-F共同修饰单层ZnS晶体结构. 采用基于密度泛函理论（DFT）的第一性原理平面波超软赝势方法，计算了各二维材料的晶体结构、稳定性、电子结构和光学性质. 计算结果表明，单层ZnS是一种准平面结构，经过修饰后则转变为褶皱六元环结构，且修饰后的ZnS具有很好的稳定性. 电子结构表明，单层ZnS是一种直接带隙半导体，其计算能隙为2.625 eV，H修饰ZnS会导致其能隙增大，且转变为间接带隙半导体，F修饰和H-F共修饰则使得ZnS能隙不同程度减小. 载流子有效质量结果显示，单层ZnS为轻空穴重电子型半导体，H或F修饰会导致半导体的空穴有效质量显著增大，电子有效质量的变化则相对较小. 光学性质表明，H, F修饰会导致ZnS的吸收边发生蓝移，其中F修饰，H-F共修饰(H与Zn同侧，F与S同侧) ZnS对短中波紫外线的吸收效果明显增强，表明其在未来光电子领域有着广阔的应用前景.

Abstract:

We study the electronic structures and optical properties of two-dimensional ZnS modified by H and F. Based on the first-principles of density functional theory (DFT), the crystal structures, stability, electronic structures and optical properties of these two-dimensional materials are calculated. The results show that the two-dimensional ZnS is a quasi-planar structure, which can transform into buckling six-membered ring structure after modification. Phonon dispersion and formation energy analysis reveal that all the chemically decorated ZnS are energetically favorable and could be synthesized. The electronic structures indicate that the two-dimensional ZnS is a direct bandgap semiconductor with energy gap of 2.625 eV. In addition, H modified ZnS will increase its energy gap and turn it into an indirect band gap semiconductor, while F modified or H-F co-modified ZnS will reduce its energy gap. The effective mass shows that the two-dimensional ZnS is a light-hole, heavy-electron type semiconductor. After H or F modification, the electron effective mass of ZnS increases significantly, but the change of electron effective mass is relatively small. Optical properties show that ZnS modified by H and F will lead to blue shift of its absorption edge, among them, the F modified and H-F co-modified (H and Zn on one side, F and S on the other) ZnS significantly enhance the absorptions of short-wavelength and middle-wavelength ultraviolet, rendering new promises in next generation high-performance electronic devices.