First Principles Study of Regulation of Monolayer ZnO and Vacancy Defects Equibiaxial Strain

The study of electronic and optical properties of ZnO/MoS2 and its vacancy heterostructures by first principles

“…To get ZnO/MoS 2 heterostructure, ZnO and MoS 2 monolayers are first established and optimized, respectively. MoS 2 monolayer has a lattice constant of 3.16 Å and ZnO monolayer has a lattice value of 3.29 Å, which are great consistent with the former theoretical calculation results [41][42][43][44]. Then, ZnO/MoS 2 heterostructures are composed of 3 Â 3 Â 1 ZnO and 3 Â 3 Â 1 MoS 2 .…”

“…The minimum value of the conduction band (CBM) and the maximum value of the valence band (VBM) are located at the high-symmetric G point and K point, respectively. As indicated in Table2, the band gaps of ZnO and MoS 2 monolayers are 1.674 and 1.747 eV, respectively, which are in good agreement with previously reported values[41,42]. The HSE06 method is further carried out to get more accurate band gaps.…”

Electronic structure of strain-tunable Janus WSSe–ZnO heterostructures from first-principles

“…The imaginary phonon modes are conned to the ZnO layer indicating that ZnO may undergo a phase transition upon application of compressive inplane biaxial strain. While prior rst-principles work studying ZnO under biaxial strain has been performed and the tunability of the electronic structure under these conditions has been reported, 25,26 it appears that the dynamical and phase stability of this material under biaxial strain have not yet been studied in detail. The phonon modes at imaginary frequencies are localized in the ZnO layer and the eigenvectors correspond to alternating out-of-plane displacements, suggesting that a phase transition could occur to a buckled structure with periodic oscillations of the directionality of the buckling and dipole moments.…”

“…20 Another 2D material that has recently begun to receive experimental and theoretical attention is monolayer ZnO, which is polar as well, with a bipartite hexagonal lattice similar to hexagonal-BN but with a small amount of buckling such that the Zn and O are close to being, but are not exactly, coplanar. [21][22][23][24][25][26][27] Monolayer ZnO is a wide band gap material, with a reported measured fundamental gap of 4.48 eV. 28 While this gap is too large for efficient absorption of visible light, the earth abundance of the constituent elements makes it a material of interest for clean energy technologies.…”

“…[21][22][23][24]28 Prior rst principles studies have investigated the electronic structure of ZnO under strain and with various defects and dopants, reporting that the band gap of ZnO can be effectively tuned by these methods, with tensile strain producing calculated band gap reductions of up to 0.5 eV at 9% tensile strain and Zn and O vacancies producing calculated band gap reductions up to 2 eV. [25][26][27] Additionally prior work has investigated the efficacy of ZnO heterostructures for water splitting applications. 29,30 To our knowledge the aqueous stability of monolayer ZnO has not been measured experimentally, however, oxides in general can exhibit stability under aqueous conditions, and are frequently used in photocatalysis.…”