Probing top-gated field effect transistor of reduced graphene oxide monolayer made by dielectrophoresis

TL;DR

This paper reports the fabrication and characterization of a top-gated field effect transistor using reduced graphene oxide monolayers created by dielectrophoresis, demonstrating ambipolar conduction and current saturation.

Contribution

It introduces a novel method to fabricate RGO monolayer FETs via dielectrophoresis and characterizes their electrical properties, including ambipolar behavior and current saturation.

Findings

RGO monolayer FETs exhibit ambipolar conduction.

Temperature coefficient of resistance matches that of exfoliated graphene.

Current saturation observed at high source-drain voltages.

Abstract

We demonstrate top-gated field effect transistor made of reduced graphene oxide (RGO) monolayer (graphene) by dielectrophoresis. Raman spectrum of RGO flakes of typical size of 5{\mu}m x 5{\mu}m show a single 2D band at 2687 cm-1, characteristic of a single layer graphene. The two probe current - voltage measurements of RGO flakes, deposited in between the patterned electrodes with a gap of 2.5 {\mu}m using a.c. dielectrophoresis show ohmic behavior with a resistance of ~ 37k{\Omega}. The temperature dependence of the resistance (R) of RGO measured between temperatures 305 K to 393 K yields temperature coefficient of resistance [dR/dT]/R ~ -9.5x10-4 K-1, same as mechanically exfoliated single layer graphene. The field effect transistor action was obtained by electrochemical top-gating using solid polymer electrolyte (PEO + LiClO4) and Pt wire. Ambipolar nature of graphene flakes is observed upto a doping level of ~ 6x1012/cm2 and carrier mobility of ~ 50 cm2V-1sec-1. The source - drain current characteristics shows a tendency of current saturation at high source - drain voltage which is analyzed quantitatively by a diffusive transport model.