Invited Paper TF+EN-WeM10
From Atom to Solid: The Structure of Amorphous ALD Thin Films and Nanolaminates

Wednesday, October 21, 2015, 11:00 am, Room 111

Atomic Layer Deposition is currently being used for a wide range of energy applications, such as photovoltaics, artificial photosynthesis, energy storage, and power semiconductor devices. In many cases the films are either very thin, well below 10 nm, or either doped or laminate materials, in which a second constituent is intercalated every few cycles.

Given the low deposition temperatures compared to other thin film processes, one of the key questions is how the microstructure of ALD materials differs from their bulk counterparts. This fundamental question of how atoms transition from isolated clusters or single monolayers to a local coordination environment characteristic of the bulk has important technological implications. Answering this question will allow us to better understand the performance of these materials as well as what makes ALD materials different, and in some cases better, to materials synthesized using other techniques.

In this talk I will discuss the impact that chemistry has on the properties and microstructure of very thin ALD films and nanolaminates of oxide dielectrics, semiconductors, and transparent conductors, comprising ZnO, HfO₂, and M:Al₂O₃ nanolaminates. By combining synchrotron X-ray characterization techniques such as X-ray Absorption Fine Structure (XAFS) and Pair Distribution Function (PDF) with in-situ techniques such as QCM and FTIR, my talk will focus on two particular problems: the evolution of coordination environment and the emergence of long-range order from the first monolayer and during the early stages of growth, and the impact that the interaction between dopant and host have in the microstructure of doped and laminate materials.