title: Quantitative Chemical Mapping of InGaN Quantum Wells from Calibrated High-Angle Annular Dark Field Micrographs.
abstract: We present a simple and robust method to acquire quantitative maps of compositional fluctuations in nanostructures from low magnification high-angle annular dark field (HAADF) micrographs calibrated by energy-dispersive X-ray (EDX) spectroscopy in scanning transmission electron microscopy (STEM) mode. We show that a nonuniform background in HAADF-STEM micrographs can be eliminated, to a first approximation, by use of a suitable analytic function. The uncertainty in probe position when collecting an EDX spectrum renders the calibration of HAADF-STEM micrographs indirect, and a statistical approach has been developed to determine the position with confidence. Our analysis procedure, presented in a flowchart to facilitate the successful implementation of the method by users, was applied to discontinuous InGaN/GaN quantum wells in order to obtain quantitative determinations of compositional fluctuations on the nanoscale.
authors.affiliation: 1Departamento de Ciencia de los Materiales e I. M. y Q. I., Facultad de Ciencias,Universidad de Cádiz,Cádiz,Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Carvalho
authors.affiliation: 1Departamento de Ciencia de los Materiales e I. M. y Q. I., Facultad de Ciencias,Universidad de Cádiz,Cádiz,Spain.
authors.forename: Francisco M
authors.initials: FM
authors.lastname: Morales
authors.affiliation: 1Departamento de Ciencia de los Materiales e I. M. y Q. I., Facultad de Ciencias,Universidad de Cádiz,Cádiz,Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Ben
authors.affiliation: 1Departamento de Ciencia de los Materiales e I. M. y Q. I., Facultad de Ciencias,Universidad de Cádiz,Cádiz,Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: García
authors.affiliation: 3IPFN,Instituto Superior Técnico,Universidade de Lisboa,Estrada Nacional 10, km 139.7,2695-066 Bobadela LRS,Portugal.
authors.forename: Andrés
authors.initials: A
authors.lastname: Redondo-Cubero
authors.affiliation: 3IPFN,Instituto Superior Técnico,Universidade de Lisboa,Estrada Nacional 10, km 139.7,2695-066 Bobadela LRS,Portugal.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Alves
authors.affiliation: 3IPFN,Instituto Superior Técnico,Universidade de Lisboa,Estrada Nacional 10, km 139.7,2695-066 Bobadela LRS,Portugal.
authors.forename: Katharina
authors.initials: K
authors.lastname: Lorenz
authors.affiliation: 5SUPA Department of Physics,University of Strathclyde,Glasgow,G4 0NG, Scotland,UK.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Edwards
authors.affiliation: 5SUPA Department of Physics,University of Strathclyde,Glasgow,G4 0NG, Scotland,UK.
authors.forename: Kevin P
authors.initials: KP
authors.lastname: O'Donnell
authors.affiliation: 6Department of Physics and Future Chips Constellation,Rensselaer Polytechnic Institute,Troy, New York 12180,USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Wetzel
keywords: EDX; HAADF-STEM; InGaN; RBS; chemical quantification