Advanced Atomic Layer Modulation Based Highly Homogeneous PtRu Precious Metals Alloy Thin Films.

Atomic layer modulation (ALM) presents a novel approach for controlling the stoichiometry of platinum-ruthenium (PtRu) alloys rather than a tedious atomic layer deposition (ALD) supercycling multielement ALD process. This method sequentially pulses dimethyl-(N,N-dimethyl-3-butene-1-amine-N)platinum (CHNPt, DDAP) and tricarbonyl(trimethylenemethane)ruthenium [Ru(TMM)(CO)] precursors with O as a counter reactant at 225 °C to produce ALM-PtRu bimetallic alloys at the nanoscale. By smartly adjusting precursor pulsing times and temperatures, the average surface composition during growth can be modulated, achieving precise control over the PtRu alloy stoichiometry. Aberration-corrected ultra-high-resolution scanning transmission electron microscope, Rutherford backscattered spectrometry, and advanced X-ray diffraction analytical tools demonstrate homogenized Pt and Ru elemental distribution without localized segregation with adjustable Pt:Ru ratios ranging from 28:72 to 97:3. Demonstrating ≈100% step coverage on the high aspect ratio (≈30) 3D trench structures (top width of 125 nm, bottom width of 85 nm), the alloy maintains uniform thickness (≈30 nm) throughout its layers. ALM-PtRu demonstrates durable and superior electrocatalytic performance compared to benchmark precious metal catalysts like ALD-Pt and ALD-Ru. This study highlights ALM's potential for precise alloy stoichiometry in PtRu films, offering significant promise for various applications, particularly electrocatalysis, and extending ALM to other metallic alloy systems.