Exchange interaction in InAs nanocrystal quantum dots |
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Authors: | U. Banin J.C. Lee A.A. Guzelian A.V. Kadavanich A.P. Alivisatos |
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Affiliation: | Department of Chemistry and Materials Science Division, University of California at Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, U.S.A. |
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Abstract: | The near band-gap level structure in high-quality colloidal InAs nanocrystal quantum dots within the very strong confinement regime is investigated. Size-selective photoluminescence excitation and fluorescence line narrowing measurements reveal a size-dependent splitting between the absorbing and the emitting states. The splitting is assigned to the confinement-enhanced electron–hole exchange interaction. The size dependence of the splitting significantly deviates from the idealized 1/r3scaling law for the exchange splitting. A model incorporating a finite barrier which allows for wavefunction leakage is introduced. The model reproduces the observed 1/r2dependence of the splitting and good agreement with the experimental data is obtained. The smaller barriers for embedded InAs dots grown by molecular-beam epitaxy, are predicted to result in smaller exchange splitting as compared with colloidal dots with a similar number of atoms. |
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Keywords: | semiconductor nanocrystal quantum dots exchange splitting InAs |
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