Gate modulated Raman spectroscopy of graphene and carbon nanotubes

• This review article gives an overview of gate modulated Raman spectroscopy.
• The basic concepts of (1) the Kohn anomaly, (2) double resonance Raman spectroscopy are included.
• The device structure and some parameters for understanding the devices are explained.
• The examples of gate modulated Raman spectroscopy are shown from our recent experimental results.

Gate-modulated Raman spectroscopy is a method of making Raman measurements while changing the Fermi energy by applying a gate voltage to the sample. In this review article, we overview the techniques of gate modulated Raman spectroscopy in graphene and carbon nanotubes (1) for assigning the combination phonon modes, (2) for understanding the optical processes involved in Raman spectra, and (3) for understanding the electron–phonon interaction not only for zone-center (q  =0) phonons but also for double resonance phonons (q≠0q≠0). The gate modulated Raman spectra are used in carbon nanotubes, too, especially for understanding electron–electron interaction from the electronic Raman spectra that are observed in metallic carbon nanotubes. Finally we discuss our recent work on gate-modulated Raman spectroscopy on bilayer graphene in which we explain how to get information about the interlayer interactions from gate modulated Raman spectroscopy.