Tuning of the electronic characteristics of ZnO nanowire transistors and their logic device application

Abstract

We present the tuning of electrical characteristics of ZnO nanowire field effect transistors (FETs) by controlling surface morphology and size of nanowires and by introducing proton-irradiation-assisted manipulation and further demonstrate their logic inverter circuit. The FETs made from surface-architecture-controlled ZnO nanowires exhibit two different types of operation modes, which are distinguished as depletion and enhancement modes in terms of the polarity of the threshold voltage. We also explain that the electrical transport behaviors are associated with the influence of surface states. In addition, we demonstrate the proton irradiation effects on the electrical characteristics of two different types of FET device structures in which the ZnO nanowires are placed on the substrate or suspended above the substrate. The photoluminescence studies of the ZnO nanowires provide substantial evidence that the observed threshold voltage shift in nanowire transistors can be explained by a surface-band-bending through the gate electric field modulation, resulting from the irradiation-induced charges. Finally, as a practical approach, we demonstrate the logic inverter circuits made from the operation mode-controlled ZnO nanowire FETs.