Dresden 2011 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 85: Poster Session II
HL 85.124: Poster
Donnerstag, 17. März 2011, 18:00–21:00, P4
Dielectric functions of wurtzite GaN at elevated temperatures — •Christian Möller1, Sviatoslav Shokhovets1, Gerhard Gobsch1, Klaus Köhler2, and Oliver Ambacher2 — 1Technische Universität Ilmenau, Weimarer Str. 32, 98693 Ilmenau, Germany — 2Fraunhofer-Institut für Angewandte Festkörperphysik, Tullastraße 72, 79108, Freiburg, Germany
Wurtzite GaN is already widely used for production of blue-ultraviolet and white light-emitting devices. In addition, numerous applications in high-power and high-temperature electronics are also possible. The knowledge of optical constants and understanding of optical processes in the vicinity of the excitonic absorption edge at room temperature as well as at elevated temperatures is crucial for the design and optimization of GaN-based devices. We carried out spectroscopic ellipsometry (SE) measurements of undoped and Si-doped c-plane epitaxial films of wurtzite GaN in a temperature range 300-800 K. The determined temperature-dependent dielectric functions (DFs) are analyzed in terms of contributions from discrete exciton states, excitonic continuum, band-to-band transitions, and phonon-assisted optical transitions into exciton-phonon complexes. Effects of Si-doping are discussed and the temperature dependence of band-gap and exciton energies and broadening parameters is presented.