Regensburg 2022 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 10: Nitrides
HL 10.1: Talk
Monday, September 5, 2022, 15:00–15:15, H34
Degradation of the electrooptical properties of UVB LEDs observed by temperature dependent electroluminescence spectroscopy — •Jakob Höpfner1, Priti Gupta1, Martin Guttmann1, Jan Ruschel2, Johannes Glaab2, Tim Kolbe2, Arne Knauer2, Tim Wernicke1, Markus Weyers2, and Michael Kneissl1,2 — 1Technische Universität Berlin, Institute of Solid State Physics, Berlin, Germany — 2Ferdinand-Braun-Institut, Berlin, Germany
The operation of UVB-LEDs induces changes in their electrooptical characteristics, especially a gradual reduction in the emission power. As the lifetime of a device is a key property for its application, it is important to understand the microscopic processes governing their degradation behavior. We report an investigation on UVB-LEDs emitting at 310 nm before and after aging for 1000 h at 100 mA (67 Acm−2) and a heatsink temperature of 70 ∘C using temperature(T)-dependent electroluminescence spectroscopy from 20 K - 340 K. Before aging, the external quantum efficiency (EQE) at 10 mA gradually increases with decreasing temperature from 0.8 % at 340 K to 1.8 % at 150 K and stays at that level for lower temperatures, indicating that EQE(T) is dominated by the radiative recombination efficiency. After 1,000 h of operation, the EQE has reduced to 0.45 % at 340 K and it shows a maximum of 1.4 % at 80 K. Also below 80 K, the EQE again decreases. These findings suggest a stress-induced reduction of both the radiative recombination efficiency and the carrier injection efficiency.