Regensburg 2025 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 33: Nitrides: Devices
HL 33.7: Vortrag
Mittwoch, 19. März 2025, 12:45–13:00, H15
Efficiency analysis of 233 nm far-UVC LEDs with varied DPD AlGaN layer thickness beyond 298 K — •Paula Vierck1, Jakob Höpfner1, Marcel Schilling1, Massimo Grigoletto1,2, Markus Blonski1, Tim Wernicke1,2, and Michael Kneissl1,2 — 1Technische Universität Berlin, Institute of Solid State Physics, Berlin, Germany — 2Ferdinand Braun Institut (FBH), Berlin, Germany
Light emitting diodes (LEDs) emitting in the far ultraviolet-C (far-UVC) spectral range offer applications in skin safe disinfection and gas sensing. In this work we analyze far-UVC LEDs with a distributed-polarization doped (DPD) p-AlGaN layer as this offers a promising alternative to Mg-doping. By compositionally grading the Al content of the AlGaN layer, a 3D hole gas can be generated exceeding the free hole concentration of conventionally Mg doped samples. The theoretically calculated charge profile depends on the grading and can be controlled by changing the DPD layer thickness or the alloy composition. In this work, five samples with DPD layer thicknesses between 25 nm and 150 nm were investigated by electroluminescence spectroscopy and numerical simulations. With decreasing DPD layer thickness we find an increase in the peak external quantum efficiency (EQE) with a maximum EQE of 0.37 % for a DPD thickness of 25 nm due to an increased hole concentration. Further analysis at temperatures of up to 353 K revealed a notable decline in the devices EQE down to 0.15 % at 353 K for a 25 nm thick DPD. This work will provide an analysis of the different contributing factors to the EQE drop with insights provided by simulations.
Keywords: LED; UVC; AlGaN; DPD layer thickness; External quantum efficiency