Abstract
A new quantitative and spatially resolved optical method was developed to quickly analyze the spatial distri-bution of multilayer graphene grown on large flat substrates, i.e., on one or more 4 '' Si wafers. An image pro-cessing analysis shows that the background-corrected reflection image of graphene on the flat substrate can be normalized so that the highest image intensity is related to the thinnest or absent layer of graphene. Which of these two most typical cases is in effect for a given sample can be easily determined by a calibration wafer using laser Raman spectroscopy 2D/G peak intensity ratio. We show that the spatial distribution of multilayer gra-phene can be determined by relating reflected light intensity from an intensity-calibrated reflection image to the layer numbers of a local graphene film. By dividing the greyscale reflection intensity into bins, the spatial multilayer graphene distribution can be visualized with a false-colored contour plot where each graphene layer quantity is represented by a unique color for easy visualization of their spatial distribution regions. The spatial distribution over extended spatial regions of multilayer graphene grown on a flat substrate, for example, a Ni or Cu films on a 4" Si or Ge wafer, can quickly be analyzed and visualized through this non-destructive charac-terization method by locally sampling and analyzing multiple regions of interest across a full spatially extended large substrate. Selected applications of this method are, for example, process uniformity and quality optimi-zation for one or more large Si wafers grown in a single batch or different batches, as well as for fast and non-destructive automated multilayer graphene growth quality control methods.