Graphene layer number determination from red-, green-, and blue-channel of optical images

Determination of graphene thickness is significant as graphene properties vary based on its layer number [1,2]. Common methods to determine layer number of graphene are Raman spectroscopy, Atomic Force Microscopy (AFM) and optical microcopy [3-5]. Although Raman and AFM offer precise characterization, these methods are time consuming and may also damage the graphene sample. On the other hand, optical microscopy is a simple and quick method. It also can be used for wide-area characterization by changing the magnification of objective lens. In this paper, layer number identification by a simple optical contrast method was demonstrated. Instead of using optical color filter, color contrast is calculated by extraction of the pixel value in red-, green and blue-channel from the captured graphene images.