Spontaneous Reactions by Atomic Hydrogen – An Extraordinary Reactant for Atomic Layer Deposition of Platinum

Atomic layer deposition (ALD) has been widely used for the deposition of platinum (Pt) nanostructures, which is conducted by using an organometallic precursor in conjunction with a reactant, commonly oxygen or hydrogen. Whereas the oxygen-based ALD processes might result in the formation of Pt oxides, especially at low temperatures, the use of hydrogen requires a relatively high temperature to initiate the chemical reactions. In this work, we investigate atomic hydrogen as a reactant for ALD of Pt using the MeCpPtMe₃ precursor by density functional theory (DFT) calculations. By calculating the reaction and activation energies for the removal of the precursor ligands by three different reactants, i.e., molecular hydrogen (H₂), molecular oxygen (O₂), and atomic hydrogen (H) following several possible pathways, we find that the reactions with atomic hydrogen are mostly barrierless and spontaneous, which contrast with the high activation and reaction energies required for the reactions with O₂ and H₂. Our study provides insights into the mechanism of the surface reactions between the precursor molecule and the reactant and highlights the significant potential of atomic hydrogen, which could pave a new way for the development of ALD of metals.