Disordered Electrical Potential Observed on the Surface of SiO$_2$ by Electric Field Microscopy

TL;DR

This study uses electric field microscopy to reveal significant surface potential fluctuations on SiO$_2$, which can influence the electronic behavior of graphene placed on it, explaining some anomalous transport phenomena.

Contribution

It provides the first detailed characterization of surface potential inhomogeneities on SiO$_2$ at ambient conditions using electric field microscopy.

Findings

Potential fluctuations up to 0.4 V within 1 μm regions

Inhomogeneous potential distribution observed on SiO$_2$ surface

Potential variations likely affect graphene charge densities

Abstract

The electrical potential on the surface of $\sim 300$ nm thick SiO$_2$ grown on single crystalline Si substrates has been characterized at ambient conditions using electric field microscopy. Our results show an inhomogeneous potential distribution with fluctuations up to $\sim 0.4 $V within regions of $1 \mu$m. The potential fluctuations observed at the surface of these usual dielectric holders of graphene sheets should induce strong variations in the graphene charge densities and provide a simple explanation for some of the anomalous behaviors of the transport properties of graphene.