Tunable electronic structure and magnetic characteristics of ZnO monolayer via vacancy defects, and domain/atomic doping

Two-dimensional ZnO monolayers have attracted great attention due to the potential applications in nano-optoelectronic and spintronic devices. However, tuning a sizeable band gap or magnetic properties is a significant challenge to the actual applications. Herein, the effects of monovacancy, divacancy, and voids defects, as well as domain/atomic doping on the electronic properties and magnetic characteristics of ZnO monolayer are investigated by spin-polarized density functional theory. The results demonstrate that single oxygen vacancy could realize the tunablity of bandgap and Zn vacancy could lead the transition between the nonmagnetic state and magnetic state. Remarkably, ZnO monolayers with different divacancies demonstrate magnetic or nonmagnetic characteristic. Zn divacancy produces the magnetic states due to the unpaired O atom, while O divacancy and Zn-O pair vacancy lead no spin polarization due to the occupied states. Void defects also can modify the magnetic properties of ZnO monolayer with the maximum magnetic moment of 1.258 μB. VI-IIA domain doping induces the nonmagnetic states, and widens or narrows the energy gap of ZnO monolayer. Additionally, ZnO monolayers with the doping of the selected atomic Rh and Ru exhibit the magnetic behavior with the total magnetic moment of 2.770 μB, and 3.678 μB, respectively. The total moments are mainly contributed by the dopants and their nearest O atoms. Our study demonstrates that the electronic properties and magnetic properties of ZnO monolayer could be effectively controlled by vacancy, divacancy, and voids as well as domain/atomic doping, being suitable for applications in optoelectronic and spintronic devices.