Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 36: ZnO: preparation and characterization II
HL 36.2: Vortrag
Mittwoch, 25. März 2009, 14:15–14:30, POT 51
Properties of reactively sputtered Ag, Au, Pd, and Pt Schottky contacts on n-type ZnO — •Alexander Lajn1, Holger von Wenckstern1, Gisela Biehne1, Holger Hochmuth1, Michael Lorenz1, Marius Grundmann1, Sandra Künzel2, Christian Vogt2, and Reinhard Denecke2 — 1Universität Leipzig, Abteilung Halbleiterphysik, Institut für ExperimentellePhysik II — 2Universität Leipzig, Physikalische Chemie der Oberflächen, Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie
The contact properties of reactively sputtered Ag, Au, Pd, and Pt Schottky contacts on nominally undoped n-ZnO thin films prepared by pulsed-laser deposition on a-plane sapphire substrates are compared. Without any surface preparation rectifying contacts were reproducibly realized by dc sputtering in an Ar/O2 atmosphere. The degree of oxidation of the contact metals was investigated by X-ray photoelectron spectroscopy (XPS). Furthermore current-voltage (IV), capacitance-voltage (CV) and capacitance-frequency (Cf ) measurements were employed. Ideality factors and barrier heights determined from IV measurements between 20 K and 300 K depend strongly on temperature indicating lateral fluctuations of the barrier potential. Considering a Gaussian distribution of barrier heights permits to describe the temperature dependence of the ideality factor and the barrier for T > 200 K. Assuming thermionic emission being the only current transport process and taking the Gaussian distribution of barrier heights into account we were able to model the entire IV characteristic (forward and reverse current for U=± 2 V) at 300 K.