Piezoelectric effect on the electronic transport characteristics of ZnO nanowire field-effect transistors on bent flexible substrates

Fabrication of bottom-gate and top-gate ZnO nanowire FETs using polymer dielectrics on plastic substrates was investigated, while the FETs were bent with various strains, where the gate electrode is located under the nanowire or on top of the nanowire. ZnO nanowires were grown on c-plane sapphire substrates by thermally vaporizing a mixed source of commercial ZnO powder and graphite powder in a ratio of 1:1 in a tube furnace. The ZnO and In₂O ₃ nanowire flexible FETs were fabricated on a PET substrate. ZnO nanowires were cast on the cross-linked PVP layer followed by patterning the source and drain electrodes. The results showed that the opposite bending phenomena between the bottom-gate and top-gate structures of ZnO nanowire flexible FETs, has been made possible by the piezoelectric effect with the electron trapping effect at the interfaces between the nanowire and polymer dielectrics.