ALD is a modified chemical vapor deposition (CVD) process for depositing thin films or nanoparticles with sub-nm precision in feature size. ALD is based on the sequential exposure of a substrate to gas-phase precursor molecules, which posses the unique characteristic of self-limiting surface chemistry. This leads to saturation of the surface with a single layer of adsorbed molecules during each exposure, allowing for conformal coating of ultra-high aspect ratio surfaces. We have developed the capability to deposit a variety of metal oxide, metal sulfide, and metallic materials by ALD. By control of the nucleation behavior of the materials, either dense films or isolated nanoparticles can be deposited on a wide range of high surface-area structures. We explore ALD chemistry through high-resolution microscopy, spectroscopy, and quantum simulations to gain atomic-scale insight into the growth and properties of these materials. In particular, we are interested in applying ALD chemistry to engineer surfaces and interfaces of energy conversion devices, which are crucial for the kinetics of charge transfer processes.
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