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

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.