Regensburg 1998 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 34: Quantenpunkte II
HL 34.10: Vortrag
Donnerstag, 26. März 1998, 18:45–19:00, H1
Size-Control and Energy-Transfer Processes for Self-Assembled InAs/GaAs Quantum Dots — •R. Heitz1,2, I. Mukhametzhanov1, A. Konkar1, P. Chen1, and A. Madhukar1 — 1Department of Materials Science and Engineering, University of Southern California, Los Angeles — 2Institut für Festkörperphysik, Technische Universität Berlin
The formation of nano-scale islands in highly strained semiconductor epitaxy has been extensively studied as means to generate optically active quantum dots (QDs). However, the intrinsic formation of islands lacks an efficient means to control the QD size. Here, we propose to exploit strain driven growth in multilayered InAs/GaAs samples, which is well known to result in vertical self-organization of islands [1], to control independently the average QD size and density. We report structural and optical investigations of MBE-grown, multilayered InAs/GaAs QD samples for various InAs deposition amounts and spacer configurations. TEM and AFM results of such stacked samples reveal an almost perfect vertical island correlation and evidence the island size to vary between the layers. PL experiments reveal a redshift of the QD ground state transition, which is mainly attributed to an increasing island size. Detailed optical investigations indicate that at low excitation densities vertical energy transfer processes suppress PL of the smaller islands in the island stacks. The dependence of the vertical energy transfer rate on the spacer configuration will be discussed.
[1] Q. Xie et al., Phys. Rev. Lett. 75, 2542 (1995)