Tunable local piezopotential properties of zinc oxide nanowires grown by remote epitaxy

Remote epitaxy has been developed recently as a new method for synthesising zinc oxide (ZnO) nanowires (NWs) with unique structural and physical properties. In this paper, the piezopotential properties and piezotronic behaviours of ZnO NWs epitaxially grown on monolayer graphene and molybdenum disulfide (MoS2) i.e., graphene-ZnO and MoS2-ZnO NWs are studied through a multiscale simulation technique. It is shown that compression is the only type of force that can efficiently trigger the piezopotential in ZnO NWs grown by remote epitaxy, since their ZnO and two-dimensional (2D) material components are weakly connected at the interfaces. Although compressed MoS2-ZnO and graphene-ZnO NWs are found to have different piezopotential distributions due to the unique polarity inversion behaviour in MoS2-ZnO NWs, the local piezopotential distribution in both ZnO NWs can be similarly modified by changing the location of 2D interlayer material. Moreover, the grapheneZnO NWs are found to possess a much larger global piezopotential difference than conventional ZnO NWs, though both ZnO NWs have the similar piezopotential distribution. Due to the unique local piezopotential property and the existence of additional peak barriers or Schottky barriers at the interfaces between ZnO NW and 2D interlayer material components, ZnO NWs grown by remote epitaxy, especially MoS2-ZnO NWs exhibit a distinct piezotronic behaviour that is significantly different from that of their conventional counterparts.