Noble Metal Alloy Thin Films by Atomic Layer Deposition & Rapid Joule Heating

Metal alloys are usually fabricated by melting constituent metals together or sintering metal alloy particles made by high energy ball milling (mechanical alloying). All these methods only allow for bulk alloys to be formed. This manuscript details a new method of fabricating Rhodium/Iridium (Rh/Ir) metal alloy films using atomic layer deposition (ALD) and rapid Joule heating induced alloying that gives functional thin film alloys, enabling conformal thin films with high aspect ratios on 3D nanostructured substrate. In this work, ALD was used to deposit Rh thin film on an Al 2 O 3 substrate, followed by an Ir overlayer on top of the Rh film. The multilayered structure was then alloyed / sintered using rapid Joule heating. We can precisely control the thickness of the resultant alloy films down to the atomic scale. The Rh@Ir alloy thin films were characterized using scanning and transmission electron microscopy (SEM/TEM) and energy dispersive spectroscopy (EDS) to study their microstructural characteristics. Grazing-incidence X-ray diffraction (GIXRD) and X-ray photoelectron spectroscopy (XPS) were also carried out to confirm the composition and formation of Rh-Ir thin film alloys. All the characterization results reveal that the Rh-Ir alloy thin film was prepared successfully with one single phase and homogeneous distribution of Rh and Ir throughout the film. Molecular Dynamics simulation experiments of Rh/Ir alloys using Large-Scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) were performed to elucidate the alloying mechanism during the rapid heating process, corroborating the experimental results.