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Title: Direct-Bandgap InAs Quantum-Dots Have Long-Range Electron--Hole Exchange Whereas Indirect Gap Si Dots Have Short-Range Exchange

Abstract

Excitons in quantum dots manifest a lower-energy spin-forbidden 'dark' state below a spin-allowed 'bright' state; this splitting originates from electron-hole (e-h) exchange interactions, which are strongly enhanced by quantum confinement. The e-h exchange interaction may have both a short-range and a long-range component. Calculating numerically the e-h exchange energies from atomistic pseudopotential wave functions, we show here that in direct-gap quantum dots (such as InAs) the e-h exchange interaction is dominated by the long-range component, whereas in indirect-gap quantum dots (such as Si) only the short-range component survives. As a result, the exciton dark/bright splitting scales as 1/R{sup 2} in InAs dots and 1/R{sup 3} in Si dots, where R is the quantum-dot radius.

Authors:
; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
974900
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 9; Journal Issue: 7, 2009
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; CONFINEMENT; EXCHANGE INTERACTIONS; EXCITONS; QUANTUM DOTS; WAVE FUNCTIONS; Basic Sciences; Energy Sciences

Citation Formats

Juo, J W, Franceschetti, A, and Zunger, A. Direct-Bandgap InAs Quantum-Dots Have Long-Range Electron--Hole Exchange Whereas Indirect Gap Si Dots Have Short-Range Exchange. United States: N. p., 2009. Web. doi:10.1021/nl901000x.
Juo, J W, Franceschetti, A, & Zunger, A. Direct-Bandgap InAs Quantum-Dots Have Long-Range Electron--Hole Exchange Whereas Indirect Gap Si Dots Have Short-Range Exchange. United States. https://doi.org/10.1021/nl901000x
Juo, J W, Franceschetti, A, and Zunger, A. 2009. "Direct-Bandgap InAs Quantum-Dots Have Long-Range Electron--Hole Exchange Whereas Indirect Gap Si Dots Have Short-Range Exchange". United States. https://doi.org/10.1021/nl901000x.
@article{osti_974900,
title = {Direct-Bandgap InAs Quantum-Dots Have Long-Range Electron--Hole Exchange Whereas Indirect Gap Si Dots Have Short-Range Exchange},
author = {Juo, J W and Franceschetti, A and Zunger, A},
abstractNote = {Excitons in quantum dots manifest a lower-energy spin-forbidden 'dark' state below a spin-allowed 'bright' state; this splitting originates from electron-hole (e-h) exchange interactions, which are strongly enhanced by quantum confinement. The e-h exchange interaction may have both a short-range and a long-range component. Calculating numerically the e-h exchange energies from atomistic pseudopotential wave functions, we show here that in direct-gap quantum dots (such as InAs) the e-h exchange interaction is dominated by the long-range component, whereas in indirect-gap quantum dots (such as Si) only the short-range component survives. As a result, the exciton dark/bright splitting scales as 1/R{sup 2} in InAs dots and 1/R{sup 3} in Si dots, where R is the quantum-dot radius.},
doi = {10.1021/nl901000x},
url = {https://www.osti.gov/biblio/974900}, journal = {Nano Letters},
number = 7, 2009,
volume = 9,
place = {United States},
year = {2009},
month = {1}
}