Diffusion mediated photoconduction in multiwalled carbon nanotube films

We present a near infrared photoresponse study of large area multiwalled carbon nanotube (MWNT) films with different electrode separations. We show that the photocurrent strongly depends on the position of the laser spot with maximum response occurring at the metal-film interface. The time constant of dynamic photoresponse is slow and increases with increasing electrode separations. The photoconduction mechanism can be explained by the Schottky barrier modulation at the metal-nanotube film interface and charge carrier diffusion through percolating MWNT networks. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3243335]