title: Effect of Threading Dislocations on the Quality Factor of InGaN/GaN Microdisk Cavities.
abstract: In spite of the theoretical advantages associated with nitride microcavities, the quality factors of devices with embedded indium gallium nitride (InGaN) or gallium nitride (GaN) optical emitters still remain low. In this work we identify threading dislocations (TDs) as a major limitation to the fabrication of high quality factor devices in the nitrides. We report on the use of cathodoluminescence (CL) to identify individual TD positions within microdisk lasers containing either InGaN quantum wells or quantum dots. Using CL to accurately count the number, and map the position, of dislocations within several individual cavities, we have found a clear correlation between the density of defects in the high-field region of a microdisk and its corresponding quality factor (Q). We discuss possible mechanisms associated with defects, photon scattering, and absorption, which could be responsible for degraded device performance.
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge , 27 Charles Babbage Road, Cambridge, CB3 0FS, U.K.
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Puchtler
authors.affiliation: School of Engineering and Applied Science, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Alexander
authors.initials: A
authors.lastname: Woolf
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge , 27 Charles Babbage Road, Cambridge, CB3 0FS, U.K.
authors.forename: Tongtong
authors.initials: T
authors.lastname: Zhu
authors.affiliation: Attolight AG , EPFL Innovation Park - Bâtiment D, CH-1015 Lausanne, Switzerland.
authors.forename: David
authors.initials: D
authors.lastname: Gachet
authors.affiliation: School of Engineering and Applied Science, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Evelyn L
authors.initials: EL
authors.lastname: Hu
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge , 27 Charles Babbage Road, Cambridge, CB3 0FS, U.K.
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Oliver
keywords: cathodoluminescence; gan; microcavities; quality factor; threading dislocations
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