Regensburg 2004 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 50: Quantenpunkte und -dr
ähte: Optische Eigenschaften III
HL 50.2: Vortrag
Freitag, 12. März 2004, 11:15–11:30, H14
Optical properties of localized excitons in InGaN quantum structures — •Til Bartel1, Matthias Dworzak1, Martin Strassburg2, Axel Hoffmann1, Andre Strittmatter1, and Dieter Bimberg1 — 1Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin — 2Georgia State University, Dep. of Physics and Astronomy, Atlanta, GA-30303
Although InGaN structures already find application in optoelectronics, its optical transitions are still poorly understood and are subject to current investigation. Indium fluctuations in InGaN quantum-wells are centers of localization for excitons and show quantum dot-like behavior at low temperatures.
Wurzite InGaN/GaN single quantum wells were grown by metal organic chemical vapor deposition on Si(111) and their luminescence was investigated. High resolution µ-photoluminescence (µ-PL) spectra of masked samples showed lines as narrow as the resolution limit. This is interpreted as an indication for δ-shaped density of states. Excitation density dependence allows the identification of excitons and biexcitones with positive and negative binding energies. Time resolved PL experiments show decay rates of less than 1 ns and investigation of temperature dependence of the photoluminescence reveal typical S-shape behavior. These results demonstrate the quantum dot-like character of the indium fluctuations.