Abstract
Femtosecond (fs) broad-band transient absorption (TA) is used to study the intra-band relaxation and depopulation dynamics of electron and hole quantized states in CdSe nanocrystals (NC's) with a range of surface properties. Instead of the drastic reduction in the energy relaxation rate expected due to a 'phonon bottleneck', we observe a fast sub-picosecond 1P-to-1S relaxation, with the rate enhanced in NC's of smaller radius. We use fs IR TA to probe electron and hole intraband transitions, which allows us to distinguish between electron and hole pathways leading to the depopulation of NC quantized states. In contrast to electron relaxation, which is controlled by NC surface passivation, depopulation of hole quantized states is extremely fast (sub-ps-to-ps time scales) in all types samples, independent of NC surface treatment (including NC's overcoated with a ZnS layer). Our results indicate that ultrafast hole dynamics are not due to trapping at surface defects, but rather arise from relaxation into intrinsic NC states.
| Original language | English |
|---|---|
| Title of host publication | Materials Research Society Symposium - Proceedings |
| Publisher | Materials Research Society |
| Pages | 211-216 |
| Number of pages | 6 |
| Volume | 536 |
| Publication status | Published - 1999 |
| Event | Proceedings of the 1998 MRS Fall Meeting - The Symposium 'Advanced Catalytic Materials-1998' - Boston, MA, USA Duration: Nov 30 1998 → Dec 3 1998 |
Other
| Other | Proceedings of the 1998 MRS Fall Meeting - The Symposium 'Advanced Catalytic Materials-1998' |
|---|---|
| City | Boston, MA, USA |
| Period | 11/30/98 → 12/3/98 |
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ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
Cite this
Electron and hole relaxation pathways in II-VI semiconductor nanocrystals. / Klimov, Victor I; Schwarz, Ch; Yang, X.; McBranch, D. W.
Materials Research Society Symposium - Proceedings. Vol. 536 Materials Research Society, 1999. p. 211-216.Research output: Chapter in Book/Report/Conference proceeding › Chapter
}
TY - CHAP
T1 - Electron and hole relaxation pathways in II-VI semiconductor nanocrystals
AU - Klimov, Victor I
AU - Schwarz, Ch
AU - Yang, X.
AU - McBranch, D. W.
PY - 1999
Y1 - 1999
N2 - Femtosecond (fs) broad-band transient absorption (TA) is used to study the intra-band relaxation and depopulation dynamics of electron and hole quantized states in CdSe nanocrystals (NC's) with a range of surface properties. Instead of the drastic reduction in the energy relaxation rate expected due to a 'phonon bottleneck', we observe a fast sub-picosecond 1P-to-1S relaxation, with the rate enhanced in NC's of smaller radius. We use fs IR TA to probe electron and hole intraband transitions, which allows us to distinguish between electron and hole pathways leading to the depopulation of NC quantized states. In contrast to electron relaxation, which is controlled by NC surface passivation, depopulation of hole quantized states is extremely fast (sub-ps-to-ps time scales) in all types samples, independent of NC surface treatment (including NC's overcoated with a ZnS layer). Our results indicate that ultrafast hole dynamics are not due to trapping at surface defects, but rather arise from relaxation into intrinsic NC states.
AB - Femtosecond (fs) broad-band transient absorption (TA) is used to study the intra-band relaxation and depopulation dynamics of electron and hole quantized states in CdSe nanocrystals (NC's) with a range of surface properties. Instead of the drastic reduction in the energy relaxation rate expected due to a 'phonon bottleneck', we observe a fast sub-picosecond 1P-to-1S relaxation, with the rate enhanced in NC's of smaller radius. We use fs IR TA to probe electron and hole intraband transitions, which allows us to distinguish between electron and hole pathways leading to the depopulation of NC quantized states. In contrast to electron relaxation, which is controlled by NC surface passivation, depopulation of hole quantized states is extremely fast (sub-ps-to-ps time scales) in all types samples, independent of NC surface treatment (including NC's overcoated with a ZnS layer). Our results indicate that ultrafast hole dynamics are not due to trapping at surface defects, but rather arise from relaxation into intrinsic NC states.
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M3 - Chapter
VL - 536
SP - 211
EP - 216
BT - Materials Research Society Symposium - Proceedings
PB - Materials Research Society
ER -