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Article | Argonne National Laboratory

New metal deposition technique offers promise for fuel cells, pacemakers

Noble metal alloys have numerous applications in microelectronics, fuel cells, and medicine. For instance, platinum-iridium alloys are used for the electrodes in pacemakers.

The ability to precisely deposit noble metal alloy thin films, particularly onto nanostructured supports, will open up new opportunities in heterogeneous catalysis, sensing, and microelectronics. 

Atomic layer deposition (ALD) is a thin film growth method currently used for the commercial production of semiconductor electronics that offers tremendous potential for realizing these opportunities, but until now the ALD of metal alloy films has not been demonstrated.

Scientists at Argonne have for the first time prepared thin metal alloy thin films using atomic layer deposition. The Argonne researchers synthesized iridium-platinum alloy films in which the Ir/Pt ratio was precisely controlled by adjusting the ratio between the ALD Ir and Pt chemical precursors.  After examining the growth mechanism, X-ray diffraction and X-ray fluorescence measurements were utilized to examine the relationship between the composition and the physical properties of these unique materials.

Next, the researchers coated deep trenches in silicon wafers with the ALD Ir-Pt alloy films and verified that the film thickness was extremely uniform along the full depth of the trenches.  This capability should open up many new technological opportunities.  Future work at Argonne will focus on extending this method to other noble metal materials as well as synthesizing noble metal alloy nanoparticles for high efficiency heterogeneous catalysts.

Citation Information: J. Elam and S. Christensen, Atomic Layer Deposition of Ir−Pt Alloy Films.” Chem. Mater., 2010, 22 (8), pp 25172525.