Regensburg 2022 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 2: Focus Session: Innovative GaN-based High-power Devices: Growth, Characterization, Simulation, Application 1
DS 2.3: Vortrag
Montag, 5. September 2022, 10:30–10:45, H17
Influence of space-charge region on luminescence in a lateral GaN superjunction — •Gordon Schmidt1, Peter Veit1, Frank Bertram1, Jürgen Christen1, Arne Debald2, Michael Heuken2,3, Thorsten Zweipfennig2, Holger Kalisch2, and Andrei Vescan2 — 1Otto-von-Guericke-University Magdeburg, Magdeburg, Germany — 2RWTH Aachen University, Aachen, Germany — 3AIXTRON SE, Herzogenrath, Germany
The superjunction concept, based on charge compensation in the drift region by fully balanced n- and p-regions, is intended to break the tradeoff between breakdown voltage and on-resistance in GaN-based power devices.
In this study, a lateral GaN p-n+ superjunction was investigated by scanning transmission electron microscope cathodoluminescence microscopy. The structure was grown on top of a GaN/sapphire template. After the growth of an AlGaN marker layer, the superjunction was epitaxially deposited composed of alternating 91 nm thick p-GaN with 5·1018 cm−3 Mg doping and 23 nm thick n+GaN with 1·1019 Si doping. Finally, the structure was capped by a n+GaN layer. To probe the space charge region of the superjunction, the luminescence evolution across the pn+p junctions was investigated at T = 16 K. Donor-acceptor-pair recombination (DAP) is dominating the spectrum in the n-doped layers. In the near-band-edge region, bound exciton luminescence is observed in GaN:Mg. Both, excitons bound to an acceptor as well as to a donor exhibit reduced intensity in the space-charge region indicating exciton dissociation by the built-in electric field.