Extremely intense Raman signals from single-walled carbon nanotubes suspended between Si nanopillars

Single-wall carbon nanotubes (SWNTs) suspended between ultra-fine Si nanopillars were characterized by microscopic Raman spectroscopy. The Raman signals from the suspended SWNTs are extremely intense, compared with those from the carbon nanotubes that grow on the flat surface of substrates and adhere tightly to the substrate surfaces. This intensity enhancement makes it possible to discriminate the Raman signals of the suspended SWNTs from these of carbon nanotubes on the substrate surface and thereby detect the signals from the suspended SWNTs selectively. Based on this novel phenomenon, the structural features of the suspended SWNTs are analyzed.