Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 96: Focus Session: Semiconductor Nanophotonics - Characterization on the Atomic Scale

HL 96.1: Topical Talk

Friday, March 30, 2012, 09:30–10:00, ER 164

Atomic Resolution Transmission Electron Microscopy of III-Nitride Nanostructues — •M. Albrecht¹, T. Schulz¹, T. Markurt¹, T. Remmele¹, A. Duff², J. Neugbauer², V. Grillo³, J.-L. Rouviere⁴, C. Nennstiel⁵, and A. Hoffmann⁵ — ¹Leibniz-Institut für Kristallzüchtung, Berlin, Germany — ²Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany — ³CNR NANO S3, Modena, Italy — ⁴CEA/INAC, Grenoble, France — ⁵TU Berlin, Institut für Festkörperphysik Berlin, Germany

The influence of compositional fluctuations on carrier localization in III-Nitride base alloys is an ongoing debate. Despite huge efforts in theory and experiment it is still controversial whether the In distribution in an InGaN quantum well is truly random or if small In enriched clusters are present. The progress in aberration corrected transmission electron microscopy offers new possibilities to study alloy fluctuations at atomic scale and with high precision. In this presentation we will summarize recent results obtained by aberration corrected transmission electron microscopy and scanning transmission electron microscopy. We will show that local strain fluctuations can be measured wit 1.5 pm precision. This allows even statistical alloy fluctuations and static atomic displacements to be analyzed in real space. We revise approaches to analyze alloy fluctuations from tetragonal lattice distortions. Our results on the alloy distribution of InGaN quantum wells are compared to optical properties measured by cathodoluminescence, photoluminescence excitation and time resolved photoluminescence.