Electrical properties of ZnO nanowire field effect transistors by surface passivation

We have synthesized single crystalline ZnO nanowires by thermal evaporation method and fabricated individual ZnO nanowire field effect transistors (FETs) to investigate their electrical properties. ZnO nanowires are strongly affected by O2 molecules in ambient. For example, surface defects such as oxygen vacancies act as adsorption sites of O2 molecules, and the chemisorption of O2 molecules depletes the surface electron states and reduces the channel conductivity. Therefore, it is important to protect the electrical properties of ZnO nanowires by surface passivation. For this purpose, we investigated the changes of the electrical properties of ZnO nanowire FETs with and without passivation by an organic material, poly(methyl metahacrylate) (PMMA). The ZnO nanowire FETs with PMMA passivation exhibited better performance in comparison with unpassivated devices.