Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 92: Poster Session: II-VI Semiconductors & ZnO and related Materials
HL 92.17: Poster
Donnerstag, 29. März 2012, 16:00–19:00, Poster D
Microscopic identification of hot spots in multi-barrier Schottky contacts on pulsed laser deposition grown zinc oxide thin films — •Stefan Müller1, Holger von Wenckstern1, Otwin Breitenstein2, Jörg Lenzner1, and Marius Grundmann1 — 1Universität Leipzig, Semiconductor Physics Group, Institut für Experimentelle Physik II, Leipzig, Germany — 2Max-Planck-Institut für Mikrostrukturphysik Weinberg 2, 06120 Halle, Germany
We report on investigations of Schottky contacts (SC) on ZnO thin films that exhibit spatially discrete variations of the barrier height. For this study we used nominally undoped ZnO thin films grown on a ZnO:Al buffer on a-plane sapphire substrates by pulsed-laser deposition. On the nominally undoped layer circular Pd(Au)Oy/ZnO-SC were fabricated by reactive dc-sputtering. The areas of the SCs are in the range from 1.8 − 44× 10−4 cm2. About 50% of the prepared SCs exhibit one or more kinks in the room temperature IV-characteristic being a clear indication for the existence of at least two different barrier heights. The characteristics were modelled by assuming a parallel connection of a respective number of individual diodes individual diodes. Using dark lock-in thermography low-barrier patches were visualized for small forward currents. Current transport at low forward voltages for low temperatures is primarily through these patches. The origin of the local decrease of barrier height was traced by energy dispersive X-ray spectroscopy on a cross section prepared by focused ion beam and is due to aluminium oxide particles in the buffer layer[1].
[1] S.Müller et al., IEEE Transaction on Electron Devices, in press.