Inelastic H Atom Scattering from Ultrathin Aluminum Oxide Films Grown by Atomic Layer Deposition on Pt(111)

Electronic and phonon spectra of thin films can be tailored by film thickness. These properties may influence energy exchange processes between the surfaces of such films and atoms or molecules. Therefore, thin films of different thicknesses and compositions have the potential to allow control over the energy transfer processes between surfaces and atoms and molecules. Atomic layer deposition was used to synthesize thin films of aluminum oxide on platinum. The films were investigated using inelastic H atom scattering and compared to single crystalline aluminum oxide and platinum crystals. The single crystals behave very differently to each other. However, single crystalline aluminum oxide and thin films of aluminum oxide grown on platinum behave nearly identically even down to the thinnest possible closed film of 1 nm. The results for alumina can be explained within a simple hard cube model. Samples with a not fully closed monolayer of aluminum oxide on platinum show two components in the energy loss spectrum of scattered H atoms: one component corresponds to scattering from the oxide layer and the second to scattering from the underlying platinum. No synergy or thickness dependent effects are observed.