Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 14: Focus Session: Site-selective Growth of single Quantum Dots

HL 14.4: Hauptvortrag

Montag, 26. März 2012, 16:45–17:15, ER 164

Spatial and spectral control of self-assembled quantum dots. — •Oliver G. Schmidt — IFW Dresden, Germany

Two major challenges in the development of quantum dot (QD) based applications are addressed in this talk: First, the need to accurately position QDs and second feasible ways to fully control their spectral properties. The first challenge has been dealt with for several years and has already matured. The second point seems more challenging and postgrowth techniques need to be developed to tune single exciton emission either to the required absolute wavelength or relative to other excitonic recombination lines. To reach these goals self assembled QDs embedded in thin GaAs nanomembranes are transferred to piezo-substrates, where large amounts of strain can be applied to the quantum dots. This technique allows shifting single QD emission lines by more than 20meV and to tune excitonic and biexcitonic lines into resonance [1]. For instance, the single QD emission can be easily tuned into resonance with certain transition lines of Rubidium atoms [2], which is important to efficiently slow down single photons on demand [3]. If embedded into a nanomembrane p-i-n device including Bragg reflectors, the wavelength, emission intensity and charging state of the QDs can be independently controlled at will [4].

[1] F. Ding et al., Phys. Rev. Lett. 104, 067405 (2010) [2] S. Kumar et al., Appl. Phys. Lett. 99, 161118 (2011) [3] N. Akopian et al., Nature Photonics 5, 230 (2011) [4] R. Trotta, P. Atkinson, J. D. Plumhof, E. Zallo, R. Razaev, S. Kumar, S. Baunack, J. R. Schröter, A. Rastelli, O. G. Schmidt, unpublished.