GO/p-TiO2 hybrid channel based depletion-mode field-effect transistors with On/Off ratio higher than 103 at room temperature

Abstract

The graphene field-effect transistor (GFET) has the severe drawback of the device turn off owing to the zero band gap of graphene that results in a limited on/off current ratio at room temperature. In this report, we propose a hybrid channel of few graphene oxide (GO) implanted with undoped p-type anatase TiO2 nanoparticles (~16 nm) to achieve a depletion type (normally-on) FET with very high on/off ratio at room temperature (300 K). The percentage of GO and TiO2 is optimized based on the performance of FET where 99 vol% GO (0.2 wt%) having 1 vol% TiO2 (0.14 M) exhibited on/off current ratio of 2.8 × 103 (ION at VGS=0 V and IOFF at VGS=1.2 V), the acceptable transconductance of 0.286 µS and high transport gap of 54.2 meV at room temperature. The remarkable performance improvement in GO/p-TiO2 hybrid FET is achieved by two distinct effects, i.e., (i) the hole accumulation in GO channel due to interfacial charge transfer between GO and p-TiO2 and (ii) the formation of high potential barrier in GO/p-TiO2/GO junctions near the Dirac point voltage.