Suspended single-wall carbon nanotubes: synthesis and optical properties

A single-wall carbon nanotube (SWNT) is a rolled-up graphene sheet, and all the carbon atoms are in the surface layer. Thus, when lying on the substrate surface, or forming a bundle, SWNTs suffer from strong interaction with the substrate atoms or other nanotubes. However, when a SWNT is suspended between mesa structures, the interactions with the substrate and other nanotubes are minimized, which is important for extracting the intrinsic properties of nanotubes. In this paper, we review the synthesis of suspended SWNTs between mesa structures and their optical properties. The first part focuses on the growth and characterization of suspended SWNTs, the mechanisms of suspended structure formation and control of the structures (individual or bundled). The second part describes photoluminescence and Raman spectroscopy of individual and ensemble SWNTs. Highly enhanced photoluminescence and Raman signals enable us to examine the structure of individual SWNTs. The third part describes device applications of suspended SWNTs.