Temperature Dependence of Single CdSe/ZnS Quantum Dots Luminescence Lifetime

Olivier Labeau (1) , Philippe Tamarat (1) , Brahim Lounis (1)

1 CPMOH - Centre de physique moléculaire optique et hertzienne

We study the temperature dependence of the luminescence decay of single CdSe/ZnS quantum dots between 2 and 140 K. For the first time, we observe a biexponential decay which was completely hidden in ensemble measurements. We find that the long time component strongly depends on temperature. This demonstrates that the band edge luminescence arises from two thermally mixed fine structure states, the dark ground state and the lowest bright one. To interpret our results, we derive the analytical expressions for the decay using a three level model. Fitting the experimental data leads directly to the lifetime of the states as well as their energy splitting.

Mots clés: single molecule detection; CdSe quantum dots; luminescence decay

Domaines: Optique [physics.optics]; Autre [cond-mat.other]

Olivier Labeau, Philippe Tamarat, Brahim Lounis. Temperature Dependence of Single CdSe/ZnS Quantum Dots Luminescence Lifetime. Physical Review Letters, 2003, 90, pp.257404. ⟨10.1103/PhysRevLett.90.257404⟩. ⟨hal-00144123⟩