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Control of the oscillator strength of the exciton in a single InGaN/GaN quantum dot
A PRL from work partly supported by the QIP IRC.
Control of the oscillator strength of the exciton in a single InGaN/GaN quantum dot
A.F. Jarjour, R.A. Oliver, A. Tahraoui, M.J. Kappers, C.J. Humphreys and R.A. Taylor
Accepted in September 2007 for publication in Physical Review Letters Nov 2007.
In this Physical Review letter, we demonstrated the control of the overlap between the electron and the hole wavefunctions of the exciton in a single InGaN/GaN quantum dot. This was achieved by applying an external electric field which leads to partial compensation of the internal piezoelectric field. Clear evidence for the increase in the overlap is provided by a measured decrease in the radiative lifetime by a factor of ~2 when half of the internal field is compensated. This was also found to be in good quantitative agreement with theoretical simulations. Furthermore, the induced increase in the overlap between the carriers wavefunctions was shown experimentally to enhance the attractive Coulomb interaction leading to a change in the sign of the biexcitonic binding energy from negative to positive. Such control may prove important for QIP-related applications, especially those in which the dipole-dipole interaction in an array of quantum dots is employed. Additionally, the accompanying control of the oscillator strength can be important when resonant coupling between electromagnetic fields and the excitonic state is sought.
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