Kelvin Probe Microscopy and Electronic Transport Measurements in Reduced Graphene Oxide Chemical Sensors

TL;DR

This study combines Kelvin Probe Microscopy and electronic transport measurements to analyze charge transfer and surface potential changes in reduced graphene oxide sensors, enhancing understanding of their chemical sensing mechanisms.

Contribution

It introduces a combined measurement approach to map local charge distribution and surface potential in RGO sensors, revealing insights into their chemical gating effects.

Findings

High selectivity and reversibility in RGO sensors

Fast response and recovery times (tens of seconds)

Ability to map local charge and identify gate-susceptible areas

Abstract

Reduced Graphene Oxide (RGO) is an electronically hybrid material that displays remarkable chemical sensing properties. Here, we present a quantitative analysis of the chemical gating effects in RGO-based chemical sensors. The gas sensing devices are patterned in a field-effect transistor geometry, by dielectrophoretic assembly of RGO platelets between gold electrodes deposited on SiO2/Si substrates. We show that these sensors display highly selective and reversible responses to the measured analytes, as well as fast response and recovery times (tens of seconds). We use combined electronic transport/Kelvin Probe Microscopy measurements to quantify the amount of charge transferred to RGO due to chemical doping when the device is exposed to electron-acceptor (acetone) and electron-donor (ammonia) analytes. We demonstrate that this method allows us to obtain high-resolution maps of the surface potential and local charge distribution both before and after chemical doping, to identify local gate-susceptible areas on the RGO surface, and to directly extract the contact resistance between the RGO and the metallic electrodes. The method presented is general, suggesting that these results have important implications for building graphene and other nanomaterial-based chemical sensors.