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HL: Fachverband Halbleiterphysik
HL 10: Nitrides
HL 10.4: Vortrag
Montag, 5. September 2022, 15:45–16:00, H34
Threshold and gain measurements of AlGaN-based UVC lasers — •Markus Blonski1, Giulia Cardinali1, Bernd Witzigmann2, Norman Susilo1, Daniel Hauer Vidal1, Martin Guttmann1, Tim Wernicke1, and Michael Kneissl1 — 1Technische Universität Berlin, Institute of Solid State Physics, Berlin, Germany — 2Department Elektrotechnik-Elektronik-Informationstechnik (EEI), University Erlangen-Nürnberg (FAU), Erlangen, Germany
Recently, first UVC laser diodes were demonstrated, with relatively high threshold current densities and pulsed operation. Critical param- eters affecting the threshold are the electron and hole wavefunctions overlap and the optical confinement factor. While thicker quantum wells (QWs) yield higher confinement factors, the wavefunctions over- lap in AlGaN QWs thicker than 3 nm is reduced due to the quantum- confined Stark effect (QCSE). In this work, the influence of QW thick- ness on lasing threshold and optical gain in AlGaN-based optically pumped lasers with SQWs between 3 nm and 12 nm emitting at 275 nm is studied. The lasing peak shifts to shorter wavelengths with respect to the spontaneous emission in thin wells, while the widest wells ex- hibit a red-shift. Similar lasing threshold power density was observed for all samples at around 1.4MW cm−2. Variable stripe length method measurements showed positive net gain in all the samples with compa- rable values of differential net gain. Simulations of the material gain show that higher energy states contribute to the gain in wider wells, whereas in the 3 nm AlGaN QW the ground state provides the gain.