Investigations on structural, electronic and optical properties of ZnO in two-dimensional configurations by
Hong-Ji Wang1, Jun-Tao Yang1,2, Chang-Ju Xu1
1School of Mathematics, Physics and Optoelectronic Engineering, Hubei University of Automotive Technology (HUAT), 167 Checheng West Road, Shiyan, Hubei Province 442002, People's Republic of China.
Abstract:
The electronic structures and optical properties of two-dimensional (2D) ZnO monolayers in a series of configurations were systematically investigated by first-principles calculations with HubbardUevaluated by the linear response approach. Three types of 2D ZnO monolayers, as planer hexagonal-honeycomb (Plan), double-layer honeycomb (Dlhc), and corrugated tetragonal (Tile) structures, show a mechanical and dynamical stability, while the Dlhc-ZnO is the most energetically stable configuration and Plan-ZnO is the second one. Each 2D ZnO monolayer behaves as a semiconductor with that Plan-, Dlhc-ZnO have a direct band gap of 1.81 eV and 1.85 eV at theΓpoint, respectively, while Tile-ZnO has an indirect band gap of 2.03 eV. Interestingly, the 2D ZnO monolayers all show a typical near-free-electron character for the bottom conduction band with a small effective mass, leading to a tremendous optical absorption in the whole visible and ultraviolet window, and this origination was further confirmed by the transition dipole moment. Our investigations suggest a potential candidate in the photoelectric field and provide a theoretical guidance for the exploration of wide-band-gap 2D semiconductors.
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