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HL: Fachverband Halbleiterphysik

HL 62: Gallium Nitride: Optical and Electronic Properties

HL 62.13: Vortrag

Mittwoch, 9. März 2016, 18:15–18:30, H17

AlN growth transition between step flow growth and step bunching — •Konrad Bellmann, Alexander Sabelfeld, Christian Kuhn, Tim Wernicke, and Michael Kneissl — Technische Universität Berlin, Institut für Festkörperphysik, Berlin, Germany

Opto-electronic devices operating in the UV range rely on smooth AlN layers with step flow morphology. This work will present a systematic study by metal organic vapor phase epitaxy of AlN layers grown on sapphire substrates to tailor the surface morphology by changing the V/III ratio and the substrate offcut angle between 0.1^∘ and 0.3^∘. At a growth temperature of 1200^∘C the transition between step bunching and step flow growth occurs at a V/III ratio of about 5 to 20. This behavior can be explained by a change of the Ehrlich-Schwöbel(ES) barrier, due to the influence of the V/III ratio on the surface energy. However, the transition additionally depends on the offcut of the sapphire substrates which has no influence on the ES barrier. Therefore, a Monte Carlo simulation is presented which is based on the surface adatom diffusion combined with a variable sticking probability at the edges. The ES barrier is implemented by differentiating between an incorporation probability at the step edge from the top or the bottom terrace.