Fabrication and electrical characteristics of dual-gate ZnO nanorod metal–oxidesemiconductor field-effect transistors

Abstract

We fabricated dual-gate ZnO nanorod metal–oxide semiconductor field-effecttransistors (MOSFETs) where a Si substrate with a 200 nm thickSiO2 layer was used as a bottom-gate and a Au electrode with a 100 nm thickSiO2 layer was used as a top-gate. From current–voltage characteristic curves of the nanorodMOSFETs, the top-gate mode operation exhibited significantly enhanced device characteristicscompared with the bottom-gate case. A switch current ON/OFF ratio of the top-gate mode(105–107) was at least one order of magnitude larger than that of the bottom-gate mode(104–106).Normalized transconductance, one of the key transistor parameters, was also drastically increased from0.34 µS µm−1 for thebottom-gate to 2.4 µS µm−1 for the top-gate mode. The enhanced device performance can be explained in terms ofgeometric field enhancement and the resulting efficient gating effect for the top-gate modegeometry.