Raman spectroscopy of graphene on GaAs
Raman spectroscopy is invaluable for studying graphene systems, however, interpreting the features of the peaks can be tricky due to sensitivity of graphene to a lot of factors such as surface effects, doping, strain, etc. In this work, the Raman processes in graphene will be reviewed and applied to the Raman spectra obtained from graphene transferred to GaAs with differing doping (n, semi-insulating, and p) via a modified wet transfer method. Raman peaks characteristic to graphene were identified and discussed. Further analysis were focused on G and 2D peaks by using Lorentzian fitting to extract information such as peak position, intensity, and width from the Raman spectra. It was found that the behavior of G peak position and G full-width at half-maximum(FWHM) supports hole doping effect on graphene where the peak position increases while the peak becomes narrower for higher hole doping. The 2D peak behavior suggests electron doping for graphene/n-GaAs sample where the 2D peak becomes suppressed as shown by the higher G to 2D intensity ratio and higher 2D FWHM for graphene/n-GaAs.