Transport Studies in Piezo-Semiconductive ZnO Nanotetrapod Based Electronic Devices

ZnO nanotetrapods (ZnO NTs) with a non-centrosymmetric structure consisting of four 1-D arms interconnected together through a central crystalline core introduce interesting piezoelectric semiconducting responses in nanorods in the bent state. Considering the widespread application of nanotetrapods in semiconductor devices, it becomes crucial to establish a coupled model based on piezoelectric and piezotronic effects to investigate the carrier transport mechanism, which is being reported here in detail for the first time. This work establishes a multiphysics coupled model of stress-regulated charge carrier transport by the finite element method (FEM), which takes full account of the wurtzite (WZ) and zinc blende (ZB) regions as well as the spontaneous polarization dependence and the dependence of the material properties on the arm orientation. It is discovered the forward gain of ZnO NT in the lateral force working mode is almost 50% more than that in the nanorod and normal force working mode while the reverse current is reduced to negligible. Through simulation calculation and analysis, it is confirmed that the piezoelectric polarization charge are able to regulate the transport and distribution of carriers in ZnO crystal, which lays a theoretical foundation for the application of piezo-semiconductive ZnO NT devices in advanced technologies.