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HL: Fachverband Halbleiterphysik
HL 32: Quantum dots and wires: preparation and characterization I
HL 32.10: Talk
Wednesday, February 27, 2008, 16:45–17:00, ER 270
Limitations of In(Ga)As/GaAs quantum dot growth — •Andrea Lenz1, Rainer Timm1, Holger Eisele1, Lena Ivanova1, Roman L. Sellin1, Huiyun Liu2, Mark Hopkinson2, Udo W. Pohl1, Dieter Bimberg1, and Mario Dähne1 — 1Technische Universität Berlin, Institut für Festkörperphysik, Germany — 2University of Sheffield, Dept. of Electronic and Electrical Engineering, UK
Large In(Ga)As/GaAs quantum dots (QDs) with an emission wavelength of 1.3 µm
are of widespread interest for devices in optoelectronics. Two different growth
strategies to achieve those larger QDs are - among others - the overgrowth with a
strain-reducing InGaAs layer [1] or the growth of InAs QDs within InGaAs quantum
wells [2].
Using cross-sectional scanning tunneling microscopy (XSTM) we studied such In(Ga)As
QD samples grown with MOCVD and MBE. In both cases the intended size increase of the
QDs is confirmed, but it is accompanied by some QDs containing a material hole, and
hence will not contribute to the luminescence. We will present atomically-resolved
XSTM images of these defects and discuss the similarities and differences between
the two samples. In addition, we developed growth models considering the strain and
the limited growth kinetics during capping, demonstrating the limits of larger QD
growth.
This work was supported by the DFG by projects Da 408/12, Da 408/13, and Sfb 296,
TP A4 and A7, as well as the SANDiE Network of Excellence of the EC.
[1] A. Lenz et al., Appl. Phys. Lett. 85, 3848 (2004)
[2] H. Y. Liu et al., Appl. Phys. Lett. 89, 073113 (2006)