Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 56: Quantum dots and wires: Preparation and characterization III
HL 56.8: Vortrag
Freitag, 31. März 2006, 12:45–13:00, POT 51
Growth-related structure of InAsN/GaAs quantum dots studied by cross-sectional scanning tunneling microscopy and spectroscopy — •L. Ivanova1, H. Eisele1, R. Timm1, A. Lenz1, M. Dähne1, O. Schumann2, L. Geelhaar2, and H. Riechert2 — 1Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany — 2Infineon Technologies, Corporate Research Photonics, 81730 München, Germany
We investigated the influence of nitrogen on the growth of quantum dots (QD) in the GaInN0.012As0.988 system using cross-sectional scanning tunneling microscopy (XSTM). The incorporation of nitrogen into the InAs/GaAs QD leads to a dissolution of the dots and the formation of cluster-like structures of InAs intermixed with N at the anionic sublattice as well as Ga at the cationic sublattice. This observation is in very good agreement with photoluminescence spectra, showing a strong decrease of the dot signal with increasing nitrogen content within the InAs layer. The nitrogen-induced dissolution of the InAs QD occurs due to the highly localized perturbation caused by N atoms.
These InAs/GaAsN heterostructures we studied further by cross-sectional scanning tunneling spectroscopy, monitoring the local density of states. The nitrogen definitely changes the band structure of the matrix material with a reduction of the fundamental band gap by about 0.2 eV and the appearance of an additional state at 0.4 eV above the conduction band minimum, as compared to pure GaAs.
This work was supported by the EU in the SANDiE Network of Excelence and by SFB 296 of the DPG, and Da 408/8.