Correlation between in Situ Raman Scattering and Electrical Conductance for an Individual Double-Walled Carbon Nanotube

In situ Raman scattering is performed on an individual semiconducting double-walled carbon nanotube (DWNT) in a field-effect transistor (FET) geometry, while the transfer characteristics of the DWNT-FET are measured. Through studying the Raman spectra with response to forward and backward gate voltage (V-gs) sweeping, respectively, we observe hysteresis loops in the curves of G(-) peak frequency and the intensity ratio of G(-) to G(+) (IG-/IG+) as a function of V-gs. These loops correlate very well with the hysteretic transfer characteristics of the device. The clear correlations suggest that G(-) peak line width and IG-/IG+. increase with the carrier concentration in the DWNT induced by V-gs. In addition, unique G(-) peak line width variations with V-gs can be attributed to interband electron transitions between the energy bands of two concentric shells of the DWNT excited by G phonons.