Raman spectroscopic image analysis on micropatterned graphene

A study has been conducted on patterned graphene with widths in the range of 0.1-4 μm which was grown by chemical vapour deposition and patterned by electron beam lithography. The microscopic behaviour of the Raman spectrum was investigated using image mapping from Raman spectroscopic data. Among three main peaks (D-band, G-band and 2D-band), the two-dimensional (2D) peak was clear even in 200 nm width graphene, however the D-band signal was very weak, confirming low defect concentration. It was found that the 2D-band line width was decreased as the width became narrower, which was explained by refining the electronic band structure because of confined sample size. The 2D- and G-band intensities were decreased by reducing the width because the laser beam spot size was greater than the width of the sample and the effective area generating the signal was reduced.