Fig. 3: Methods for extracting figures of merit of film quality from optical scans.
From: Layer-by-layer assembly yields thin graphene films with near theoretical conductivity
A An optical scan of one of the films fabricated in the study. The differing regions observed in the film are highlighted, green showing uncovered substrate where breaks in the film formed, orange showing homogeneous film coverage, and blue showing regions of material aggregation. B A histogram of extinction values calculated for a sample of 100000 pixels from the image in (A). C Image of another film with more homogeneous film quality without full substrate coverage. D Image extinction histogram from the image in (C). Shown in the inset is how the substrate’s extinction, <Ext>substrate is determined, such that it may be subtracted from the average extinction in the image to yield the average film extinction <Ext>film. Also shown, how the substrate pixel sum Σsubstrate is determined by integration of the histogram curve, which is used to determine film coverage. E shows how the film perimeter is determined for a sample image, by binarization of the image between film and substrate domains as shown in (F) and then using particle analysis to find the sum of the perimeter of the boundary between the two regions, the result of which can be seen in (G).
