title: Distinguishing cubic and hexagonal phases within InGaN/GaN microstructures using electron energy loss spectroscopy.
abstract: 3D InGaN/GaN microstructures grown by metal organic vapor phase epitaxy (MOVPE) and molecular beam epitaxy (MBE) have been extensively studied using a range of electron microscopy techniques. The growth of material by MBE has led to the growth of cubic GaN material. The changes in these crystal phases has been investigated by Electron Energy Loss Spectroscopy, where the variations in the fine structure of the N K-edge shows a clear difference allowing the mapping of the phases to take place. GaN layers grown for light emitting devices sometimes have cubic inclusions in the normally hexagonal wurtzite structures, which can influence the device electronic properties. Differences in the fine structure of the N K-edge between cubic and hexagonal material in electron energy loss spectra are used to map cubic and hexagonal regions in a GaN/InGaN microcolumnar device. The method of mapping is explained, and the factors limiting spatial resolution are discussed.
authors.affiliation: School of Physics, H. H. Wills Physics Laboratory, University of Bristol, Bristol, BS8 1TL, United Kingdom.
authors.forename: I J
authors.initials: IJ
authors.lastname: Griffiths
authors.affiliation: School of Physics, H. H. Wills Physics Laboratory, University of Bristol, Bristol, BS8 1TL, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Cherns
authors.affiliation: ETSIT-ISOM, Universidad Politécnica de Madrid, 28040 Madrid, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Albert
authors.affiliation: ETSIT-ISOM, Universidad Politécnica de Madrid, 28040 Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Bengoechea-Encabo
authors.affiliation: ETSIT-ISOM, Universidad Politécnica de Madrid, 28040 Madrid, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Angel Sanchez
authors.affiliation: ETSIT-ISOM, Universidad Politécnica de Madrid, 28040 Madrid, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Calleja
authors.affiliation: Osram Opto Semiconductors GmbH, Leibnizstrasse 4, 93055, Regensburg, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Schimpke
authors.affiliation: Osram Opto Semiconductors GmbH, Leibnizstrasse 4, 93055, Regensburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Strassburg
keywords: EELS; InGaN micro-structures; STEM; light emitting diodes