Regensburg 2025 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 33: Nitrides: Devices
HL 33.4: Vortrag
Mittwoch, 19. März 2025, 12:00–12:15, H15
Studying the carrier distribution of multicolor far-UVC LEDs by temperature dependent electroluminescence measurements — •Jakob Höpfner1, Franz Biebler1, Florian Kühl1, Marcel Schilling1, Anton Muhin1, Massimo Grigoletto1,2, Martin Guttmann2, Gregor Hoffmann3, Friedhard Römer3, Tim Wernicke1, Berndt Witzigmann3, and Michael Kneissl1,2 — 1Technische Universität Berlin, Institute of Solid State Physics, Berlin, Germany — 2Ferdinand-Braun-Institut (FBH), 12489 Berlin, Germany — 3Lehrstuhl für Optoelektronik, Department EEI, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany
The low current injection efficiency (CIE) is one of the root causes for the poor external quantum efficiency of AlGaN based far-UVC LEDs. To improve the CIE it is necessary to gain insights into the carrier distribution and transport in the AlGaN multiple quantum well active region. Therefore, heterostructures were grown by metalorganic vapour phase epitaxy (MOVPE) with a varying number of QWs (2 –20) emitting at 233 nm and one single QW with an emission wavelength of 250 nm. This allows us to probe the carrier transport with the help of temperature dependent electroluminescence measurements (100 K - 340 K). The experimental findings were correlated with drift-diffusion simulations and Monte-Carlo ray-tracing simulations. Experiment and simulations show that the holes are weakly confined in the 233 nm emitting QWs and exhibit a long diffusion length over many QWs mainly due to thermal escape from the shallow barriers.
Keywords: AlGaN; UV-LED; ultraviolet; temperature; characterisation