Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 100: ZnO and its relatives

HL 100.2: Talk

Friday, March 20, 2015, 09:45–10:00, EW 203

Characterization of the p-GaAs / n-ZnO tunnel contact system for opto-electronic applications — •Christian Koppka, Andreas Nägelein, Katja Tonisch, and Thomas Hannappel — Technische Universität Ilmenau, FG Photovoltaik, 98693 Ilmenau, Deutschland

Nanowire based concepts for optoelectronic applications such as LEDs, sensors and solar cells are current global research areas. In contrast to axial structures, the front contacting of nanowire structures with radial configuration is more challenging. In this regard, we examine the contacting of p-doped GaAs nanowire shells using AlOx and ZnO:Al to realize a tunnel junction at the interface. To achieve a good contact system we investigate a ALD type growth of AlOx and ZnO:Al layers for the homogeneous coating of non-planar surfaces in a conventional MOCVD reactor (AIX 200). Due to the very limited analysis methods for coated nanowires structures, the characterization of the p-GaAs/AlOx/n-ZnO system was carried out on planar samples. Current-voltage measurements reveal an ohmic behavior between TCO and III-V material and confirm the applicability of the contact system. By depth-resolved auger electron spectroscopy measurements no diffusion processes of Al or As were found. Accordingly, a sharp interface is assumed. Our ALD process was used successful on nanowire structures and reveal a homogeneous coating.