Regensburg 2019 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 24: Nitrides: Preparation and characterization I
HL 24.7: Vortrag
Mittwoch, 3. April 2019, 11:15–11:30, H31
Optical properties of homoepitaxial AlGaN/GaN MQWs — •Markus Schleuning1, Markus Wagner1, Benjamin Damilano2, and Axel Hoffmann1 — 1Technische Universität Berlin, Berlin, — 2CRHEA-CNRS, Valbonne, France
AlGaN/GaN MQWs with varying well thickness, Al barrier content and number of stacks were grown by homoepitaxial MBE on c-plane GaN substrates and investigated using PL, TRPL and CL spectroscopy. The quantum well structures exhibit a low surface roughness of RRMS ≈ 0.3 nm. The MQW emission energies could be adjusted between 3.3 eV and 3.5 eV as function of well width and Al composition of the barrier. TRPL measurements reveal radiative lifetimes between 0.5 ns and 0.5 µs. The luminescence shift to lower energies and increase of lifetimes are interpreted as consequence of the quantum confined Stark effect (QCSE) that has its origin in piezoelectric and spontaneous polarization fields. Furthermore localization energies at 10 K of up to 30 meV are found using temperature resolved PL. Especially the 3 nm thick MQWs show efficient free exciton luminescence with a FWHM of only 40 meV at 300 K caused by large exciton binding energies in the confined structure.