Optical Thickness Determination of Graphene by Color

Graphene, and multi-layered graphene, are single atomic layers of carbon, with remarkable electrical properties. This makes it a highly valuable material across scientific and technological fields. Accurate thickness determination is essential, as many of the electrical properties are layer dependent; however, typical methods are slow. This thesis investigates a non-invasive optical method for estimating graphene thickness by correlating RGB color values from microscope images with step height measurements obtained via atomic force microscopy (AFM). Graphene flakes were exfoliated onto a SiO₂/Si substrate, imaged under white light illumination, and analyzed using ImageJ to extract color values. Results show that red-channel contrast offers the closest agreement with theory for flakes under ~12 nm, supporting its use as a practical tool for rapid screening.