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/R2 in InAs dots and 1/R3 in Si dots, where R is the quantum-dot radius.
Publication Year: 2009
Publication Date: 2009-06-15
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
Access and Citation
Cited By Count: 17
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