Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 60: Focus Session: Coherent dynamics in semiconductor nanostructures and coupled devices
HL 60.4: Topical Talk
Mittwoch, 13. März 2013, 16:45–17:15, H16
Optical Properties of coupled InAs submonolayer depositions in GaAs — •Udo W. Pohl1, Thomas Switaiski2, Ulrike Woggon2, Jan-Hindrik Schulze1, Tim D. Germann1, and André Strittmatter1 — 1Inst. f. Festkörperphysik, TU Berlin, Germany — 2Inst. f. Optik und Atomare Physik, TU Berlin, Germany
Localized states formed in a stack of InAs submonolayer depositions separated by few monolayer thick GaAs spacer layers recently received much advertence for optoelectronic applications. A high areal density [1] and direct relaxation into localized quantum dot (QD) states not coupled to a wetting layer are interesting for, e.g., direct modulated high-speed lasers [2]. On the other hand, coupling of stacked submonolayer depositions to a Stranski-Krastanow (SK) QD layer provides a tuning ability for the carrier dynamics and the transition energies.
The talk outlines the structural and optical properties of InAs/GaAs submonolayer stacks and reports on the carrier dynamics of such stacks coupled to a layer of SK QDs beneath. In the coupled system, the radiative recombination rate is controlled by the separation to the SK QDs. The measured dynamics is well described by a numerically simulated population of states localized in the submonolayer stack coupled to those of the SK QDs, taking Fermi blocking into account.
[1] A. Lenz et al., Atomic structure of buried InAs sub-monolayer depositions in GaAs, Appl. Phys. Express 3, 105602 (2010).
[2] F. Hopfer et al., 20 Gb/s 85∘C error-free operation of VCSELs based on submonolayer deposition of quantum dots, IEEE J. Sel. Top. Quantum Electron. 13, 1302 (2007).