Hole-hole and electron-hole exchange interactions in single InAs/GaAs quantum dots

Received 5 December 2008; revised manuscript received 26 January 2009; published 17 March 2009 A combined analysis of microphotoluminescence PL and microphotoluminescence excitation PLE spectra of the same single quantum dot QD enables an unambiguous identification of four sharp resonances in the excitation spectrum detected on the positive trion transition h0 →e0h0h1 and reveals the complete fine structure of the hot trion. Transitions into states normally forbidden by spin selection rules for optical transitions between pure spin states are observed. The splittings of all triplet states are found to be large up to 3m eV, asymmetric, and QD size and shape dependent. The experimental data are in excellent agreement with theoretical calculations in the framework of eight-band k·p theory and the configuration-interaction method. To account for the physical effects which lead to the observed fine-structure splitting, parts of the complex model are successively omitted. This approach identifies the anisotropic hole-hole exchange interaction as well as correlation effects dominating the observed fine-structure splitting of the hot trion.