Raman spectroscopy of pristine and PEI-doped graphene
Graphene is a promising sensing material due to its high specific area, high electrical conductivity, and low electrical noise. In this work, the n-type doping of monolayer graphene on SiO2/Si by polyethylenimine (PEI) coating and exposure to methanol vapor was investigated using Raman spectroscopy. Pristine graphene was single- and double-coated with PEI via spin-coating. Doping effectiveness was evaluated based on the changes in the Raman features, such as peak position, FWHM, and intensity ratios, of the signature graphene band peaks. In-situ Raman measurements were obtained before, during, and after exposure to methanol in order to investigate the interaction of the gas adsorbates on the graphene surface. The doping method using volatiles can be employed as a gas sensing mechanism of pristine graphene.