Sample-charged mode scanning polarization force microscopy for characterizing reduced graphene oxide sheets

Abstract

A unique operation mode of scanning polarization force microscopy (SPFM) was developed for characterizing reduced graphene oxide (rGO) sheets that were individually charged, mainly by monitoring the change of the sample's apparent height along with its surface potential. The principles and features of this sample-charged mode SPFM (SC-SPFM) were introduced. By comparing with other scanning-probe based techniques that characterize the surface electrical properties, including the traditional tip-biased mode SPFM, electrostatic force microscopy, and Kelvin probe force microscopy, it was found that the SC-SPFM has higher sensitivity and lateral resolution. Furthermore, by monitoring charge transfer between two rGO sheets with SC-SPFM, the “good” or “bad” contacts related to junction geometry at the nanometer scale can be visualized clearly.