title: Extremely efficient multiple electron-hole pair generation in carbon nanotube photodiodes.
abstract: We observed highly efficient generation of electron-hole pairs due to impact excitation in single-walled carbon nanotube p-n junction photodiodes. Optical excitation into the second electronic subband E22 leads to striking photocurrent steps in the device I-V(SD) characteristics that occur at voltage intervals of the band-gap energy E(GAP)/e. Spatially and spectrally resolved photocurrent combined with temperature-dependent studies suggest that these steps result from efficient generation of multiple electron-hole pairs from a single hot E22 carrier. This process is both of fundamental interest and relevant for applications in future ultra-efficient photovoltaic devices.
authors.affiliation: Laboratory of Atomic and Solid-State Physics, Cornell University, Ithaca, NY 14853, USA. nmg32@cornell.edu
authors.forename: Nathaniel M
authors.initials: NM
authors.lastname: Gabor
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Zhong
authors.forename: Ken
authors.initials: K
authors.lastname: Bosnick
authors.forename: Jiwoong
authors.initials: J
authors.lastname: Park
authors.forename: Paul L
authors.initials: PL
authors.lastname: McEuen
mesh_terms: D004560:Electricity; D004583:Electrons; D036103:Nanotechnology; D037742:Nanotubes, Carbon; D055095:Optics and Photonics; D017785:Photons; D013696:Temperature
chemical_list: D037742:Nanotubes, Carbon