with an acquisition time of 0.5 min per image, which is considerably fast compared to conventional Raman microscopy. Each image includes 4000 Raman spectra. The spectra were analyzed using Lorentzian fitting for the D, G, and 2D peaks to extract peak positions ω, intensities I, and widths Γ (see Experimental Details). Figure (b) shows the mean Raman spectrum of the GFET #1, and