Figure shows the Raman spectra for the rest GFETs. The D-band was not well fitted owing to the low intensity, validating the high quality of the graphene films. The single Lorentzian profile of the 2D peak ensures the films comprise single-layer graphene, aligning with a flat optical contrast as observed in Figure (a). density nH and compressive strain ε, which were calculated using vector decomposition (see Experimental Details). Figure (f) and (g) show the nH and ε images, which also reveal micrometer-scale variations within the channel. The nH inhomogeneities likely arise from several sources: (i) PMMA residues, 37 oxygen, and/or moisture adsorbed from the atmosphere; 40 (ii) trapped charges and dangling bonds in the underlying SiO2 substrate; and/or (iii) residual ions trapped at the graphene/SiO2 interface during the Cu etching and PMMA/graphene rinsing stages. The ε inhomogeneities are likely due to localized suspension of graphene, which otherwise conforms to the undulating SiO2 substrates owing to van der Waals interactions. No clear correlation was observed between the nH and ε images (Figure (f) and (g)), suggesting that the primary source for nH was not related to ε, although the strain may induce charge inhomogeneity through rehybridization of π-σ bonds and vice versa. Raman Analysis across a GFET Array. The same analysis was extended across all GFETs on the chip, totaling 54 GFETs. The complete image acquisition time for the array was 30 min, which meets demands for industrial applications. Figure shows the ωG-ω2D plots for each GFET.