Highly dispersed Co deposited on Al 2 O 3 particles via CoCp 2  + H 2 ALD

Highly dispersed cobalt atoms were deposited on porous alumina particles using atomic layer deposition (ALD) with a CoCp /H chemistry at approximately 7 wt%. H did not completely reduce the cyclopentadienyl organic ligands bound to deposited Co atoms at ALD reaction conditions. A sharp decline in Co deposited per cycle for two or more ALD cycles indicates that much of the Al O surface is sterically blocked from further CoCp deposition after the first CoCp exposure. Temperature programmed reduction confirmed that the adsorbed precursor organic ligands persist after H exposures during ALD and temperatures as high as 500 °C are required to fully reduce the organic ligands to CH . High resolution, element sensitive imaging showed that Co atoms were dispersed on the Al O surface and could deposit in previously unobserved multiple growth morphologies, specifically layers that were continuous over several angstroms or discrete nanoparticles. Density functional theory calculations were used to examine Co atom adsorption, show the altered haptic binding of cracked Cp ligands, and to calculate the thermodynamics of Cp ligand decomposition. The lateral steric hindrance between organic ligands bound to deposited Co atoms, Cp ligand decomposition mechanism, and local Al O surface termination all likely determine the observed Co growth morphology during initial ALD cycles.