title: Thermionic emission and tunneling at carbon nanotube-organic semiconductor interface.
abstract: We study the charge carrier injection mechanism across the carbon nanotube (CNT)-organic semiconductor interface using a densely aligned carbon nanotube array as electrode and pentacene as organic semiconductor. The current density-voltage (J-V) characteristics measured at different temperatures show a transition from a thermal emission mechanism at high temperature (above 200 K) to a tunneling mechanism at low temperature (below 200 K). A barrier height of ∼0.16 eV is calculated from the thermal emission regime, which is much lower compared to the metal/pentacene devices. At low temperatures, the J-V curves exhibit a direct tunneling mechanism at low bias, corresponding to a trapezoidal barrier, while at high bias the mechanism is well described by Fowler-Nordheim tunneling, which corresponds to a triangular barrier. A transition from direct tunneling to Fowler-Nordheim tunneling further signifies a small injection barrier at the CNT/pentacene interface. Our results presented here are the first direct experimental evidence of low charge carrier injection barrier between CNT electrodes and an organic semiconductor and are a significant step forward in realizing the overall goal of using CNT electrodes in organic electronics.
authors.affiliation: Nanoscience Technology Center, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, Florida 32826, USA.
authors.forename: Biddut K
authors.initials: BK
authors.lastname: Sarker
authors.forename: Saiful I
authors.initials: SI
authors.lastname: Khondaker
mesh_terms: D004553:Electric Conductivity; D004566:Electrodes; D004574:Electromagnetic Fields; D004579:Electron Transport; D008422:Materials Testing; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure*; D009279:Naphthacenes / Q000737:chemistry*; D010316:Particle Size; D012666:Semiconductors; D013499:Surface Properties
chemical_list: D037742:Nanotubes, Carbon; D009279:Naphthacenes; C523499:pentacene