Can impact excitation explain efficient carrier multiplication in carbon nanotube photodiodes?
basic_science · Level V
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- Record sourced from PubMed, PMID 20681526.
- Also identified by DOI 10.1021/nl100639h.
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Abstract
We address recent experiments (Science 2009, 325, 1367) reporting on highly efficient multiplication of electron-hole pairs in carbon nanotube photodiodes at photon energies near the carrier multiplication threshold (twice the quasi-particle band gap). This result is surprising in light of recent experimental and theoretical work on multiexciton generation in other confined materials, such as semiconducting nanocrystals. We propose a detailed mechanism based on carrier dynamics and impact excitation resulting in highly efficient multiplication of electron-hole pairs. We discuss the important time and energy scales of the problem and provide analysis of the role of temperature and the length of the diode.