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TEM 3-beam study of annealing effects in InGaNAs using ab-initio structure factors for strain-relaxed supercells

Müller, K.; Schowalter, M.; Rubel, O.; Hu, D. Z.; Schaadt, D. M.; Hetterich, M.; Gilet, P.; Fritz, R.; Volz, K.; Rosenauer, A.

Abstract:
We report on a Transmission Electron Microscopy 3-beam technique based on the interference of 000, 200 and 220. Nonlinear imaging artefacts are eliminated by Fourier filtering, yielding 200 and 220 lattice fringe images, from which chemically sensitive contrast and strain are measured, respectively. In this way, In and N composition can be mapped at atomic scale in quaternary InGaNAs by comparison with simulated reference data. Our Bloch wave simulations are based on structure factors derived from supercells with 106 atoms, which have been strain-relaxed by valence force field methods. Additionally, the influence of electron redistributions due to chemical bonding is accounted for by modified atomic scattering amplitudes derived from density functional theory. By comparing local compositions in an annealed In0.28Ga0.72N0.025As0.975 sample with its as-grown counterpart, we find homogenisation of InGaNAs layer thickness and -stoichiometry upon annealinng


Zugehörige Institution(en) am KIT Institut für Angewandte Physik (APH)
Publikationstyp Zeitschriftenaufsatz
Jahr 2011
Sprache Englisch
Identifikator ISSN: 1742-6588
KITopen ID: 1000027181
Erschienen in Journal of Physics: Conference Series
Band 326
Heft 1
Seiten 012026/1 - 5
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