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Title: Size Dependence of Two-Photon Absorption in Semiconductor Quantum Dots

Abstract

Quantum confinement plays an important role in the optical properties of semiconductor quantum dots (QDs). In this work, we combine experiment and modeling to systematically investigate the size dependence of the degenerate two-photon absorption (TPA) of below-band-gap radiation in CdSe QDs. The TPA coefficient β at 800 nm of CdSe QDs of varying radii was measured using femtosecond white-light transient absorption spectroscopy by probing the pump-induced bleaching at the first exciton transition energy. β was also calculated using a model based on the multiband effective-mass approximation. Satisfactory agreement between experiment and theory was obtained. Our findings show the evolution of the TPA in the QDs from that of atom-like to bulk-like with increasing the radius R. The TPA coefficient (or the volume normalized TPA cross-section) increases with radius approximately linearly in the strong confinement regime due to the rapid increase of the joint density of states for the two-photon allowed transitions, and saturates for R > 5 nm (the exciton Bohr radius), approaching that of bulk CdSe.

Authors:
 [1];  [1]
  1. Case Western Reserve Univ., Cleveland, OH (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1192936
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 114; Journal Issue: 1; Journal ID: ISSN 0021-8979: JAPIAU
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English

Citation Formats

Dakovski, Georgi L., and Shan, Jie. Size Dependence of Two-Photon Absorption in Semiconductor Quantum Dots. United States: N. p., 2013. Web. doi:10.1063/1.4811349.
Dakovski, Georgi L., & Shan, Jie. Size Dependence of Two-Photon Absorption in Semiconductor Quantum Dots. United States. https://doi.org/10.1063/1.4811349
Dakovski, Georgi L., and Shan, Jie. 2013. "Size Dependence of Two-Photon Absorption in Semiconductor Quantum Dots". United States. https://doi.org/10.1063/1.4811349.
@article{osti_1192936,
title = {Size Dependence of Two-Photon Absorption in Semiconductor Quantum Dots},
author = {Dakovski, Georgi L. and Shan, Jie},
abstractNote = {Quantum confinement plays an important role in the optical properties of semiconductor quantum dots (QDs). In this work, we combine experiment and modeling to systematically investigate the size dependence of the degenerate two-photon absorption (TPA) of below-band-gap radiation in CdSe QDs. The TPA coefficient β at 800 nm of CdSe QDs of varying radii was measured using femtosecond white-light transient absorption spectroscopy by probing the pump-induced bleaching at the first exciton transition energy. β was also calculated using a model based on the multiband effective-mass approximation. Satisfactory agreement between experiment and theory was obtained. Our findings show the evolution of the TPA in the QDs from that of atom-like to bulk-like with increasing the radius R. The TPA coefficient (or the volume normalized TPA cross-section) increases with radius approximately linearly in the strong confinement regime due to the rapid increase of the joint density of states for the two-photon allowed transitions, and saturates for R > 5 nm (the exciton Bohr radius), approaching that of bulk CdSe.},
doi = {10.1063/1.4811349},
url = {https://www.osti.gov/biblio/1192936}, journal = {Journal of Applied Physics},
issn = {0021-8979: JAPIAU},
number = 1,
volume = 114,
place = {United States},
year = {2013},
month = {1}
}