Atmospheric adsorption on pristine and nitrogen-doped graphene: doping-dependent, spatially selective

Abstract

Using Raman and photoemission spectroscopy, we probe the atmospheric adsorption on pristine and nitrogen p -doped graphene supported by SiO2/Si. Laser annealing in vacuum led to a pronounced change in Raman spectra parameters, corresponding to a decrease in hole density due to adsorbate removal from the sample surface. We found that the shift inversely correlates with a degree of initial nitrogen doping, and thus less p -type adsorption doping takes place on graphene with a higher density of charge carriers with the same sign. The amount of hole doping required for the absence of atmospheric adsorption doping was found to be p noad = (3.87 ± 0.31) × 1013 cm−2 (~2.3% of pyridine-like nitrogen), while the electronic doping required to fully compensate adsorption hole doping was nequil = (0.46 ± 0.12) × 1013 cm−2 (~0.2% of graphitic nitrogen). We showed that atmospheric adsorption on pristine graphene increases the spatial charge carrier inhomogeneity; in contrast, the adsorption on nitrogen-doped graphene shows a spatially selective nature and reduces the inhomogeneity of charge carriers. This study is useful for graphene applications which require specific adsorption properties, as well as for taking these properties into account when designing graphene-based nanoelectronic devices.