Extremely Efficient Multiple Electron-Hole Pair Generation in Carbon Nanotube Photodiodes
Nathaniel M. Gabor,1,*
Zhaohui Zhong,2,
Ken Bosnick,4
Jiwoong Park,3
Paul L. McEuen1,2
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-VSD characteristics that occur at voltage intervals of the
band-gap energy
EGAP/
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.
2 Center for Nanoscale Systems, Cornell University, Ithaca, NY 14853, USA.
3 Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
4 National Institute for Nanotechnology, National Research Council of Canada, Edmonton, AB T6G 2M9, Canada.
Present address: Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109, USA.
* To whom correspondence should be addressed. E-mail: nmg32{at}cornell.edu
