Metal Semiconductor Interface Growth Using Electrochemical Atomic Layer Deposition (ALD)

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Technical: This project aims for further understanding and demonstration of electrochemical atomic layer deposition (ALD) for the formation of high quality solid state nanostructures under ambient conditions (aqueous solutions). Electrochemical ALD is where surface limited electrochemical reactions such as underpotential deposition (UPD) are used for ALD. Metal and semiconductor solid state interfaces: metal/metal, semiconductor/metal, metal/semiconductor, and semiconductor/semiconductor, will be formed atomic layer by atomic layer and characterized during ALD growth using surface science methodologies. Outcomes expected are an expanded understanding of electrochemical ALD, and practical information about which materials can be grown, on which substrates and with what quality. The study of a new type of electrochemical surface limited reaction, surface limited redox replacement (SLRR), allowing ALD formation of metals will also be pursued to explore interface formation using ultra high vacuum (UHV) surface analysis techniques such as LEED, Auger, and XPS. In-situ STM will be used to follow surface atomic structure. Nanostructure formation will be performed in a thin layer flow electrodeposition system, and characterized in-situ using an electrochemical quartz crystal microbalance (EQCM) flow cell system, as well as using an in-situ STM flow cell system. Interfaces are a primary component of layered electronic and photonic materials, and thus can be atomic and electronic structure determining factors. Studies of the layer by layer growth of solid state interfaces has been limited primarily to molecular beam epitaxy (MBE), in ultrahigh vacuum, at high temperatures. These studies will be the first systematic investigations of layer by layer growth of metal and semiconductor solid state interfaces as they form in aqueous solutions at room temperature. Non-technical: The project addresses basic research issues in a topical area of materials science with high technological relevance, and is expected to provide unique opportunities for graduate and undergraduate student training in interdisciplinary research across materials science, chemistry, and surface physics. Educational impacts of this project involve minority students at the graduate, undergraduate, and pre high school levels. The PI has an established record of working with minorities, having taught six minority undergraduate students, and had six minority graduate students, two of which are currently in his group, and two have gone on to faculty positions at research institutions. At the pre high school level, the PI has begun a program 'Drum Majors for Science' (DMS) designed to bring science into predominantly minority elementary schools to capture the minds of young students while they are still interested in science, before they move on through middle and High school. He plans to incorporate faculty, graduate, and undergraduate students in repeated visits. Presentations are to involve short power point lectures, demonstrations, hands on experiments, and general question and answer time to stimulate and encourage student curiosity.