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DS: Fachverband Dünne Schichten

DS 9: Layer Properties: Electrical, Optical, and Mechanical Properties

DS 9.6: Vortrag

Dienstag, 1. April 2014, 11:30–11:45, CHE 91

The Origin of the Radial Distribution of the Electronic and Structural Properties of Magnetron Sputtered ZnO:Al Thin Films — •André Bikowski¹, Thomas Welzel², and Klaus Ellmer¹ — ¹Helmholtz-Zentrum Berlin, D-14109 Berlin — ²Technische Hochschule Mittelhessen, D-35390 Gießen

We investigated the electronic and structural properties of magnetron sputtered ZnO:Al films by means of radially resolved X-ray diffraction, resistivity, and plasma process monitor measurements.

It is known for a long time now that films sputtered onto stationary substrates exhibit a pronounced radial distribution of their electronic and structural properties. Mainly there exist two explanations for this effect: (i) The inhomogeneities are caused by excess oxygen reaching the substrate surface or (ii) they are due to a bombardment of the growing films by high energetic oxygen.

We were able to clearly correlate the radially resolved ion energy distribution spectra of high energetic negative oxygen ions to the electronic and structural properties of the films, and hence found model (ii) to be more appropriate. Since these high energetic negative ions exhibit energies in the range of several hundred eV in the case of DC sputtering, and the formation energies of defects in ZnO are some 10 eV only, a strong impact of the high energetic ions on the structural and the related electronic properties is to be expected. Generally, the results show a decisive role of high energetic oxygen for magnetron sputtering, which has to be taken into account also for other TCO materials such as In₂O₃:Sn or SnO₂:F.