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HL: Fachverband Halbleiterphysik

HL 47: Transport in high magnetic field/quantum-Hall-effect

HL 47.2: Talk

Thursday, March 29, 2007, 16:00–16:15, H14

Investigation of CdSe/ZnSe quantum dots by surface sensitive x-ray diffraction — •Isabella Gierz, Christian Kumpf, and Eberhard Umbach — Experimentelle Physik II, Universität Würzburg, Am Hubland, 97074 Würzburg

In semiconductor heterostructure systems with a lattice mismatch of a few percent between substrate and epilayer nanometer-sized islands form spontaneously during growth. Within these islands electrons are confined in all three dimensions. For future quantum dot applications islands with homogeneous size distribution, a high surface density, and a defect free crystal lattice are needed.

We investigated CdSe/ZnSe quantum dots with a lattice mismatch of 7%. Grazing incidence x-ray diffraction measurements were performed at the BW2 beamline of HASYLAB using the Risø six-circle diffractometer. The data was analyzed using an iso-strain model developed by I. Kegel [1]. This method allows to determine height, lateral radius, gradient of relaxation, and chemical composition of the islands. Furthermore, we present model calculations for reciprocal space maps and results from AFM measurements to verify the results obtained by Kegel’s method.

[1] I. Kegel et al "Nanometer-Scale Resolution of Strain and Interdiffusion in Self-Assembled GaAs/InAs Quantum Dots", Phys. Rev. Lett. 85, 8 (2000).