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HL: Fachverband Halbleiterphysik

HL 25: Poster Session: GaN - Optical Properties & Preparation and Characterization & Devices

HL 25.17: Poster

Montag, 26. März 2012, 16:00–19:00, Poster D

Ultraviolet photoluminescence spectroscopy of homo- and heteroepitaxially grown AlN — •Christoph Reich¹, Viola Küller², Arne Knauer², Martin Feneberg³, Jessica Schlegel¹, Markus Weyers², Rüdiger Goldhahn³, and Michael Kneissl^1,2 — ¹Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany — ²Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany — ³Otto-von-Guericke-Universität, Abteilung Materialphysik, Universitätsplatz 2, 39106 Magdeburg, Germany

For high power deep UV LEDs, high quality AlN templates are required. However, heteroepitaxial growth of AlN on sapphire substrates leads to high threading dislocation densities (TDD) of 10¹⁰ cm⁻², which significantly deteriorate the internal quantum efficiency of LEDs. The optical properties of homoepitaxially grown AlN layers on bulk AlN and heteroepitaxially grown AlN layers on patterned and unpatterned AlN/sapphire templates have been investigated by low temperature photoluminescence spectroscopy (PL), temperature dependent PL and excitation density dependent PL. High quality AlN layers are grown homoepitaxially on bulk AlN substrates (TDD < 10⁸cm⁻²) or epitaxial lateral overgrowth (ELO) of patterned AlN/sapphire templates (TDD < 10⁹cm⁻²) by metalorganic vapour phase epitaxy (MOVPE). The recombination of free excitons and several donor bound excitons has been observed. Exciton emission energies, exciton linewidths and the temperature dependence PL for different substrate materials will be compared.