Low Operating Voltage Single ZnO Nanowire Field-Effect Transistors Enabled by Self-Assembled Organic Gate Nanodielectrics

Abstract

The development of nanowire transistors enabled by appropriate dielectrics is of great interest for flexible electronic and display applications. In this study, nanowire field-effect transistors (NW-FETs) composed of individual ZnO nanowires are fabricated using a self-assembled superlattice (SAS) as the gate insulator. The 15-nm SAS film used in this study consists of four interlinked layer-by-layer self-assembled organic monolayers and exhibits excellent insulating properties with a large specific capacitance, 180 nF/cm2, and a low leakage current density, 1 x 10(-8) A/cm2. SAS-based ZnO NW-FETs display excellent drain current saturation at Vds = 0.5 V, a threshold voltage (Vth) of -0.4 V, a channel mobility of approximately 196 cm2/V s, an on-off current ratio of approximately 10(4), and a subthreshold slope of 400 mV/dec. For comparison, ZnO NW-FETs are also fabricated using 70-nm SiO2 as the gate insulator. Implementation of the SAS gate dielectric reduces the NW-FET operating voltage dramatically with more than 1 order of magnitude enhancement of the on-current. These results strongly indicate that SAS-based ZnO NW-FETs are promising candidates for future flexible display and logic technologies.