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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 Heuken^2,3, 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.