Figure 4. Patterning graphene with a steel mask by applying an inhomogenous vertical magnetic field in UV ozonation.

(a) Optical microscope image and zoom-in scanning electron micrograph (inset) of the steel mask. The scale bar in the inset is 20 μm. (b) Optical microscope image of a graphene pattern, and (c) its high-resolution SEM image. (d) Micro-Raman map of the D band intensity in the region as denoted in (c). (e) Evolution of Raman spectra for the dots outlined by the green rectangle in (d).