Berlin 2005 – scientific programme

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HL: Halbleiterphysik

HL 58: Poster IIb

HL 58.68: Poster

Tuesday, March 8, 2005, 16:30–19:00, Poster TU F

Growth of highly homogeneous InGaAs islands on GaAs using a stressor layer technique — •H. J. Krenner, D. Heiss, D. Schuh, M. Bichler, G. Abstreiter, and J. J. Finley — Walter Schottky Institut and Physik Department,TU Muenchen, Am Coulombwall 3, D-85748 Garching, Germany

We present a detailed study of single and multi-layer structures containing self-assembled InGaAs islands on GaAs. Growth parameters were optimized in order to observe a transition to low QD surface densities for optical single QD spectroscopy. As a stressor layer we introduced a highly strained 3nm InGaAs quantum well 10nm below the islands. We observe a pronounced blue-shift of the QD emission and furthermore in improved homogeneity resulting in a narrower linewidth (FWHM <20meV). We attribute these effects to altered growth conditions on the strained surface. First studies of multi-layer structures indicate that this novel stressor layer technique enables preparation of a well defined strained surface for the first QD layer. The buffer thickness between the following QD layers can be set to achieve similar strain conditions for each layer. This is the opposite approach compared to proposed strain-reduction layers since it takes advantage of island growth on strained substrates to achieve homogeneous ensembles. Variation of In-content and buffer layer thicknesses gives rise to a versatile technique which is particularly attractive to grow active media for laser applications.