Substitutional Boron Doping of Graphene using Diborane in CVD

Abstract This paper reports on a few layer boron doped graphene with high homogeneity, stability and size. To achieve this, we employed diborane to synthesize a boron doped graphene film in a CVD system. During synthesis, we investigated the effect of diborane flow and growth time on copper foil to optimize doped graphene growth conditions. Raman spectroscopy, XPS, EDXS and ellipsometer were employed for the characterization of the doped graphene films. The results of our study enabled the design of a recipe for thin film boron doped graphene growth with optimum optical transmission values. We further found that increasing the flow of diborane from 10 to 30 sccm and growth times from 10 to 30 min leads to the formation of thicker graphene films. However, we discovered that a few layer graphene film with high homogeneity could be obtained for the film that was grown using 10 sccm diborane along with 30-min growth time. The doping was confirmed by observing the shift in the Raman spectra peaks and XPS measurements in comparison to single layer pristine graphene. The study also revealed that boron atoms substituted carbon atoms in the honeycomb structure as confirmed by XPS measurements, which also provide the doping rate to be 2.4%. Our study has significant implications regarding substitutional doping which enables the doping to be stable for a long time, and this is crucial for the doped graphene to be employed in semiconducting technology particularly in optoelectronics.