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HL: Fachverband Halbleiterphysik

HL 28: Focus Session: Breakthroughs in wide-bandgap semiconductor laser diodes II

HL 28.4: Talk

Wednesday, March 29, 2023, 16:15–16:30, POT 251

Temperature dependent electroluminescence studies of the carrier transport in multi colour deep ultraviolet light emitting diodes — •Jakob Höpfner¹, Florian Kühl¹, Marcel Schilling¹, Anton Muhin¹, Gregor Hofmann², Friedhard Römer², Tim Wernicke¹, Bernd Witzigmann², and Michael Kneissl¹ — ¹Technische Universität Berlin, Institute of Solid State Physics, Berlin, Germany — ²Lehrstuhl für Optoelektronik, Department EEI, Friedrich-Alexander-Universität, Erlangen-Nürnberg, German

Earlier studies have shown that a drop in current injection efficiency (CIE) is partly responsible for the poor external quantum efficiencies (EQE) of AlGaN-based deep ultraviolet light emitting diodes (DUV-LEDs). In particular, the hole injection and the carrier distribution in the AlGaN multi quantum well (MQW) active region is not well understood. In order to get a better insight we have performed temperature dependent electroluminescence (EL) investigations of three-fold AlGaN MQW LEDs with two of the QWs emitting at 233 nm and one QW emitting at 250 nm. In addition, the position of the 250 nm QW with the MQW structure was varied. From temperature dependent EL measurements we observe a strong shift in the intensity distribution over wavelength and temperature. We were able to correlate this with a change in the hole injection into the different QWs suggesting an efficient hole transport over the barriers between the QWs at room temperature. These experimental results are also supported by devices simulations and enable us to further improve the LED heterostructure.