Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 50: Gallium Nitride: Fabrication and Characterization

HL 50.7: Vortrag

Mittwoch, 9. März 2016, 11:30–11:45, H17

MOVPE growth and characterization of GaN based tunnel junctions employing highly Ge-doped GaN — •Silvio Neugebauer, Aqdas Fariza, Marc Hoffmann, Gordon Schmidt, Hartmut Witte, Jürgen Bläsing, Frank Bertram, Armin Dadgar, Jürgen Christen, and André Strittmatter — Institute of Experimental Physics, Otto-von- Guericke-University Magdeburg, Germany

GaN-based p-n tunnel junctions (TJs) are effective means to improve lateral current spreading in surface emitting light-emitting diodes and lasers. Owing to the large bandgap of GaN and the limited achievable acceptor and donor concentration by Mg and Si doping, respectively, the realization of effective TJs by metalorganic vapor phase epitaxy (MOVPE) is challenging. Ultra-high donor concentrations in MOVPE-grown GaN have been recently demonstrated by Ge doping. In this study, we have successfully used different growth sequences to prepare GaN-based TJs. In particular, the growth sequence at the transition from highly p-doped to highly n-doped material is critical for achieving a sufficient tunneling probability. Furthermore, the activation process for the Mg-doped GaN layer has to be optimized. We will compare thermal annealing schemes on mesa structures and unprocessed TJ structures as well as electron beam irradiation for its effective acceptor activation. First results on LED devices will also be presented and the mechanism responsible for the tunneling process will be discussed.