Carrier doping from adsorbed H2O molecules to single-walled carbon nanotubes (SWCNTs) has been examined using an optical approach. SWCNTs with the diameter of about 3 nm were employed in order to observe the Drude absorption (AD), the first and the second inter-subband absorption (A11 and A22, respectively), and absorption associated with adsorbed water molecules (Aw) simultaneously in Fourier transform infrared absorption measurements. The following spectral variations were recognized with exposing SWCNTs to water vapor: (i) AD is enhanced, (ii) A11 is suppressed, (iii) A22 is unaffected, and (iv) Aw peaks are enhanced. The carrier density evaluated with the Drude model has been found to increase with increasing the exposure time. Judging from this correlation, it is strongly suggested that the carrier is injected from adsorbed water molecules to the first subband of semiconducting SWCNTs.
Physics of Semiconductors: 30th International Conference on the Physics of Semiconductors
- Pub Date:
- December 2011
- carbon nanotubes;
- electronic structure;
- thin films;
- Photon- and electron-stimulated desorption;