Exchange interaction in InAs nanocrystal quantum dots

✍ Scribed by U. Banin; J.C. Lee; A.A. Guzelian; A.V. Kadavanich; A.P. Alivisatos

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 315 KB
• Volume: 22
• Category: Article
• ISSN: 0749-6036
• DOI: 10.1006/spmi.1997.0504

✦ Synopsis

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 confinementenhanced electron-hole exchange interaction. The size dependence of the splitting significantly deviates from the idealized 1/r 3 scaling law for the exchange splitting. A model incorporating a finite barrier which allows for wavefunction leakage is introduced. The model reproduces the observed 1/r 2 dependence 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.