RAMAN SPECTROSCOPY OF GRAPHENE AND GRAPHENE DEVICES

Irene Calizo, Guangjun Cheng, and Angela R. Hight Walker

Physics Laboratory, NIST, Gaithersburg, MD

Due to its potential applications in the electronics, energy, and aeronautics industries, graphene has attracted the interest of many in the scientific community.  It exhibits extraordinary properties such as high carrier mobility, thermal conductivity and stiffness leading to ultra sensitive chemical detectors, field effect transistors, transparent electrodes, and interconnects.   Recent advances in chemical vapor deposition based growth and transfer onto Si/SiO2 substrates produces scaleable, large area monolayer graphene compatible with present semiconductor processing technology.  Raman spectroscopy has proven to be fast, nondestructive, non-contact, and high throughput tool to distinguish the number of graphene layers and quantify the disorder and electron-phonon coupling.  Graphene’s Raman spectrum contains two prominent features, the G peak at ~1580 cm-1 and a G’ band at ~2700 cm-1.  A D peak at 1350 cm-1 appears at the edges or in the presence of defects.  A novel combined AFM/Raman instrument facilitates sub-diffraction mapping, thereby providing additional information about edge effects and serves as a quality indicator of the graphene.  Furthermore, Raman spectra of gated graphene devices provide information about electron phonon interactions near the Dirac point.  Here we present our recent Raman work on graphene and graphene devices produced by mechanical exfoliation of bulk graphite, chemical vapor deposition, and epitaxially grown graphene on SiC.