Regensburg 2007 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 23: Symposium: In situ Optics III

DS 23.4: Vortrag

Donnerstag, 29. März 2007, 10:45–11:00, H34

In-situ Spectroscopic Ellipsometry studies of MOVPE grown new materials: InN and InGaN — •Martin Leyer¹, Massimo Drago¹, Markus Pristovsek¹, Wolfgang Richter², and Michael Kneissl¹ — ¹Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, Germany — ²Univ. di Roma "Tor Vergata", Dip. di Fisica, Via Ricerca Scientifica 1, 00133 Italy

Indium rich nitride semiconductors are especially challenging to grow, resulting in yet unresolved discussions on some of their basic properties, i.e. the fundamental bandgap energy. Our investigations have shown that spectroscopic ellipsometry is a very powerful tool for in-situ growth analysis of InN and related alloys. We have characterized in-situ several MOVPE grown InN layers of varying structural qualities in the energy range between 1,6 eV and 6,5 eV prior to contamination due to exposure to air. In this work we present a model for the dielectric function of InN. Analysis of the shift of the critical points of InN with the temperature allowed the determination of the temperature dependence of the InN optical properties between 300 K and 900 K. Such model could be used quantitatively to determine in-situ the InN growth rate as well as to determine surface effects such as roughening and accumulation of metallic Indium on the surface of the growing layer. The now known optical properties of the binary systems InN and GaN are used to approximate InGaN layers. Since we have found that ellipsometry is extremely sensitive to the formation of metallic Indium surfaces we are also investigating Indium segregation in InGaN quantum wells.