Correlating defect density with carrier mobility in large-scaled graphene films: Ramanspectral signatures for the estimation of defect density

Abstract

We report a correlation between carrier mobility and defect density in large-scaledgraphene films prepared by chemical vapor deposition (CVD). Raman spectroscopyis used for investigating the layer number and the crystal quality of graphenefilms, and the defect density is estimated by the intensity ratios of the Dand G peaks. By carefully controlling the growth parameters, especially theH2/CH4 ratios during growth,and employing H2 during cooling, monolayer-dominant graphene films can be obtained with different D peakintensities in Raman spectra, which show good correspondence with their carrier mobilityobtained by Hall measurements. Also, a progressive shift of neutrality points to a morenegative gate voltage is observed with the increase in defect density. Both the connectionsof carrier mobility and the shift of neutrality points to a negative direction in relation tothe defect density in graphene are observed for the first time in CVD-grown graphene films.With the best growth conditions, a cm-scaled graphene film with carrier mobility of ∼ 1350 cm2 V − 1 s − 1 (p-type in air) can be obtained.