Facile and Reliable Determination of Multilayer Graphene Thickness using Optical Microscopy

Abstract

Optical transmittance of exfoliated multilayer graphene (MLG) was investigated and cross-referenced with a standard monolayer sample. Plots of grayscale values against position on the images were found to have step-like profiles. Step heights were extracted from the profiles and found to have peak points. The peaks occurred at approximately 80 layers region. These findings occurred due to interlayer interactions within the samples, with the layers being the transition from MLG to the bulk graphite. Contrast difference (Cd) on the samples was found to vary linearly with the number of graphene layers. These results showed optical transmittance of , and for a monolayer, bilayer, trilayer and tetralayer, respectively. The exponential decrease in transmittance with number of graphene layers has been attributed to variations in optical absorption of the incident light by the MLG samples.