Dresden 2009 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 26: Poster II

DS 26.49: Poster

Mittwoch, 25. März 2009, 09:30–12:30, P5

In situ noise measurements on ion bombarded thin films: 1/f-noise as a fingerprint for amorphization — •Matthias Noske, Moritz Trautvetter, and Paul Ziemann — Institut für Festkörperphysik, Universität Ulm, D-89081 Ulm

As has been experimentally demonstrated, the crystalline binary alloy In₂Au can be transformed into an amorphous state by low temperature ion irradiation¹. This transformation can be followed by measuring the ion induced increase of the electrical resistance as a function of the ion fluence. While this increase can be attributed to the built-up of static disorder, fluctuating atomic configurations may be present as well leading to resistance fluctuation and, as a consequence, to 1/f noise. To test such a possibility, patterned AuIn₂ films were irradiated with 350 keV Ar⁺ ions of various fluences up to 10¹⁵ ions/cm² at 85 K. During the stepwise amorphization noise density SR spectra of the 1/f noise were taken by applying a correlation measurement technique² allowing detection of signals below the thermal noise. It could be shown that the spectral noise density is maximal at the percolation limit whereas the resistance approaches its final value.
¹ B. Heinz, P. Ziemann, Nucl. Instr. And Meth. B 132, 589 (1997).
² A.H. Verbruggen, H. Stoll, K. Heeck, R. H. Koch, Appl. Phys. A 48, 233 (1989).