Correlation of p-doping in CVD Graphene with Substrate Surface Charges

Research output: Contribution to journalArticle

Authors

  • S. Goniszewski
  • M. Adabi
  • O. Shaforost
  • L. Hao
  • N. Klein

Colleges, School and Institutes

External organisations

  • Imperial College London
  • National Physical Laboratory
  • Department of Materials

Abstract

Correlations between the level of p-doping exhibited in large area chemical vapour deposition (CVD) graphene field effect transistor structures (gFETs) and residual charges created by a variety of surface treatments to the silicon dioxide (SiO2) substrates prior to CVD graphene transfer are measured. Beginning with graphene on untreated thermal oxidised silicon, a minimum conductivity (σmin) occurring at gate voltage Vg = 15 V (Dirac Point) is measured. It was found that more aggressive treatments (O2 plasma and UV Ozone treatments) further increase the gate voltage of the Dirac point up to 65 V, corresponding to a significant increase of the level of p-doping displayed in the graphene. An electrowetting model describing the measured relationship between the contact angle (θ) of a water droplet applied to the treated substrate/graphene surface and an effective gate voltage from a surface charge density is proposed to describe biasing of Vg at σmin and was found to fit the measurements with multiplication of a correction factor, allowing effective non-destructive approximation of substrate added charge carrier density using contact angle measurements.

Details

Original languageEnglish
Article number22858
JournalScientific Reports
Volume6
Publication statusPublished - 9 Mar 2016

ASJC Scopus subject areas