Nanotubes are High Mobility Semiconductors

Abstract. The electron transport properties of a very long (20 micron) CVD-grown nanotube are reported. In this device the transport is dominated by intrinsic scattering processes at room temperature. The room temperature hole mobility is 20,000 cm2/Vs, exceeding that of technologically-relevant semiconductors. The mobility increases with decreasing temperature, and is estimated to be greater than 180,000 cm2/Vs at 470 mK. Single-walled carbon nanotubes (SWNTs) are currently being considered for revolutionary applications in nanolectronics. While metallic SWNTs have been shown to conduct electrons ballistically over micron lengths at room temperature, the picture of electron transport in semiconducting SWNTs is less clear. Transport in semiconducting SWNTs synthesized via laser ablation has been previously interpreted as diffusive, with a low mobility (~20 cm2/V·s) [1]. However electrostatic force microscopy (EFM) [2] and low temperature transport [3] measurements on similar devices indicate that the conduction is limited by a series of large transport barriers. EFM measurements on semiconducting SWNTs grown by chemical vapor deposition instead show diffusive conduction with a long mean free path. Here we study electro