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Controlling point defect populations in AlGaN deep UV LEDs

D. Cameron1,2, M. Schilling3, G. Kusch4, P.R. Edwards2, V. Spulis4, T. Wernicke3, M. Kneissl3,5, R.A. Oliver4, and R.W. Martin2

Published in:

Nanotechnology, vol. 37, no. 20, pp. 205702, doi:10.1088/1361-6528/ae659c (2026).

Abstract:

Point defects are known to degrade LED performance by lowering efficiencies, maximum output power and device lifetimes. Here we show that growth temperature is a key variable, affecting bothpoint defect concentrations and distributions. Cathodoluminescence and electron beam induced current measurements elucidate the role these defects play in carrier recombination within thewells. Combining such measurements with atomic force microscopy allows us to identify the growth mechanisms at play and help explain the point defect distributions observed. We find thatin all cases, the presence of threading dislocations with a screw component LED to the formation of spiral hillocks. Desorption of gallium along ridges and wide atomic terraces lead to blue-shiftedquantum well emission energies but also impacted point defect populations. As growth temperatures were increased, dislocation mediated gettering counteracts a rising population of point defects. This restricts their impact below 1060°C, above which, performance regresses and point defects dominate.

1 Gatan, Inc. Pleasanton, CA 94588, United States of America
2 Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG, United Kingdom
3 Institute of Solid State Physics, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany
4 Department of Materials Science and Metallurgy, University of Cambridge, CB3 OFS Cambridge, United Kingdom
5 Ferdinand-Braun-Institut, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany

Keywords:

AFM, cathodoluminescence, dislocations, EBIC, point defects, time resolved spectroscopy, UV LED

© 2026 The Author(s). Published by IOP Publishing Ltd.Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

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