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HL: Fachverband Halbleiterphysik

HL 85: Poster Session II

HL 85.16: Poster

Donnerstag, 17. März 2011, 18:00–21:00, P4

UV photoluminescence spectroscopy of AlGaN alloys with different Al-contents — •Christoph Reich, Jessica Schlegel, Joachim Stellmach, Patrick Vogt, and Michael Kneissl — Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany

AlGaN alloys are very promissing materials for ultraviolet (UV) light emitting diodes and lasers in the spectral range between 360 nm and 200 nm. However, for high efficiency devices further improvement of material quality and better understanding of the optical properties is needed. In order to investigate the influence of the composition and defect density on the emission characteristics we have characterized AlGaN layers with different Al-content using temperature dependent and excitation power dependent UV photoluminescence (PL) spectroscopy. The samples were grown by metalorganic vapor phase epitaxy either on (0001) GaN/sapphire or on (0001) AlN/sapphire to minimize lattice mismatch within the entire composition range. We observe a decrease in the PL intensity and an increase in the full width at half maximum with higher Al-content, which can be attributed to a reduction of the crystal quality as well as an increase in composition fluctuation. The emission characteristics and the temperature dependence of the bandgap energy for different AlGaN compositions will be discussed.