Dresden 2017 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 50: Nitrides: Preparation and Characterization

HL 50.4: Talk

Wednesday, March 22, 2017, 10:30–10:45, POT 251

Improving lateral current spreading of InGaN LEDs by MOVPE grown GaN tunnel junctions — •Silvio Neugebauer, Andreas Lesnik, Florian Hörich, Hartmut Witte, Jürgen Bläsing, Armin Dadgar, and André Strittmatter — Institute of Experimental Physics, Otto-von- Guericke-University Magdeburg, Germany

Improving current injection into nitride-based p/n-junction devices is an important task for further enhancement of the efficiency of light-emitting diodes (LEDs) and vertical cavity surface emitting lasers. GaN-based homoepitaxial p/n tunnel junctions could be an effective means to improve lateral current spreading and still maintain high optical transparency. However, the effectiveness of the tunnel junction is limited due to the achievable maximum donor and acceptor concentrations as well as the activation of hydrogen passivated Mg acceptors buried beneath an n-type GaN layer. In this study, we have grown heavily doped GaN:Mg/GaN:Ge tunnel junctions on top of conventional LED structures using exclusively metal-organic vapor phase epitaxy (MOVPE). In particular, the activation process of the Mg-doped GaN layer is critical for device performance. We will compare post-growth thermal annealing schemes applied to LED mesa structures with thermal annealing of the p-type GaN:Mg layer during growth with regard to the efficiency of the activation. Furthermore, we currently investigate the potential of MOVPE regrowth of the GaN:Ge layer on top of an an ex-situ activated GaN:Mg layer.