Dresden 2020 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 30: Poster I
HL 30.25: Poster
Tuesday, March 17, 2020, 13:30–15:45, P3
Effect of Mg doping in the electron blocking layer on UVC-LED efficiency characterized by temperature–dependent electroluminescence spectroscopy — •Katharina Müller1, Priti Gupta1, Norman Susilo1, Martin Guttmann1, Tim Wernicke1, Markus Weyers2, and Michael Kneissl1,2 — 1Technische Universität Berlin, Institute of Solid State Physics, Berlin, Germany — 2FBH, Berlin, Germany
The external quantum efficiency (EQE) of UVC emitters crucially depends on the Mg doping profile in the LED heterostructure. In this study, a series of flip-chip mounted AlGaN-based UVC-LEDs with different Mg doping in the electron blocking layer (EBL) is investigated using temperature–dependent (100 K - 330 K) electroluminescence spectroscopy. During the growth, the Cp2Mg/group-III precursor ratio (x) in the EBL layer was varied with x = 0.155%, 1.0% and 1.5%. At 330 K and 10 mA, LEDs with x = 1.0% show higher EQE (up to 0.28%) compared to LEDs with x = 0.155% (EQE: 0.11%) and x = 1.5% (EQE: 0.15%). This difference between different doping levels becomes more pronounced with decreasing temperature. While the EQE increases with decreasing temperature for x = 1.0% with a maximum at around 210 K, the EQE for x = 0.155% and 1.5% continuously decreases or remains very low with lowering temperature. This indicates a higher injection efficiency in LEDs with x = 1%, in comparison to x = 0.155% and x = 1.5%. The optimal doping profile in the EBL was found to be at around x = 1.0%, leading to an improved carrier injection and thus higher EQE.