Size-dependent oscillator strength and quantum efficiency of CdSe quantum dots determined by controlling the local density of states
| Abstract | We study experimentally time-resolved emission of CdSe quantum dots inan environment with a controlled local density of states (LDOS). Thedecay rate is measured versus frequency and as a function of distance toa mirror. We observe a linear relation between the decay rate and theLDOS, allowing us to determine the size-dependent quantum efficiency andoscillator strength. We find that the quantum efficiency decreases withincreasing emission energy mostly due to an increase in nonradiativedecay. For the first time, we manage to obtain the oscillator strengthof the important class of CdSe quantum dots. The oscillator strengthvaries weakly with frequency in agreement with behavior of quantum dotsin the strong confinement limit. Surprisingly, the measured absolutevalues are a factor of 5 below theoretically calculated values. Ourresults are relevant for applications of CdSe quantum dots inspontaneous emission control and cavity quantum electrodynamics. |
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| Authors | M. D. Leistikow, J. Johansen, A. J. Kettelarij, P. Lodahl, and W. L. Vos |
| Year of publication | 2009 |
| Date published | 01/2009 |
| Journal | Phys. Rev. B |
| Volume | 79 |
| Pages | 045301: 1-9 |
| DOI number | 10.1103/PhysRevB.79.045301 |
| Keywords | LDOS, quantum description of interaction of light and matter, quantum dots, time resolved luminescence |