Stickney, a professor of chemistry at the University of Georgia, will speak on "Electrochemical Atomic Layer Deposition (ALD)" as part of the Institute's nanotechnology seminar series. Abstract: Recent results in studies of the formation of compound and metal nanofilms by electrochemical atomic layer deposition (ALD) will be discussed. ALD is the deposition of materials an atomic layer at a time using surface limited reactions. Electrochemical surface limited reactions are generally referred to as underpotential deposition or UPD. By combining UPD and ALD, electrochemical ALD is created. Historically most electrochemical ALD has been performed in the creation of compound semiconductor thin films. More recently a number of elemental deposits have been formed by electrochemical ALD, and a surface limited reaction referred to here as a surface limited redox replacement or SLRR. Recent work on the formation of compound for photovoltaics, thermoelectrics, and for phase change memory may be discussed. In addition, recent work on the growth of Pt and Ru nanofilms for fuel cell electrodes may be described. Deposit characterization involves electron beam microprobe analysis (EPMA) for deposit stoichiometry. Glancing angle X-ray diffraction for structural characterization, while scanning tunneling microscopy (STM) was used to characterize the surface morphology. Optical characterization involves reflection absorption studies as well as photoelectrochemical studies. Optimization studies involve systematic investigation of the conditions which result in the formation of one compound or elemental monolayer with each deposition cycle. In general, deposits formed at a rate of one monolayer per cycle or less show the best structure, stoichiometry and morphology. Nano templates can be used to form nanoclusters, rods or wires, depending on the number of cycles performed. Superlattices can be formed by alternating some finite number of cycles for the growth of one compound with a similar number of cycles of another. X-ray diffraction can then be used to characterize the period of the superlattice. Bio: John Stickney received his BS in Chemistry from Humboldt State University in 1981, and a Ph.D. in Chemistry from the University of California, Santa Barbara, in 1984. He worked under the direction of Professor Arthur Hubbard, and his dissertation was titled “Metal Deposition on Well-Defined Platinum Electrodes”, which was the first study of the surface structures formed by underpotential deposition (UPD). He then joined the faculty of the University of Georgia in 1985 as an Assistant Professor of Chemistry. At UGA, John began a program to study Cu single crystal surfaces in aqueous electrolytes, with the idea that to understand electrodeposition you must first understand the substrate structure, and Cu was a substrate of great importance in electrodeposition. After learning about atomic layer epitaxy (ALE) he was encouraged to find out if UPD could be applied, and this resulted in a redirection of his research efforts, and a patent in 1994. ALE is a subset of atomic layer deposition (ALD), and the development of electrochemical ALD has since been the focus of his research. Recently, John started a company (Electrochemical ALD L.C.) to produce ALD equipment and is exploring the range of materials that can be formed by ALD. His work focuses on chemistry at the interfaces of metals, semiconductors, etc.
Nano@Tech with Dr. John Stickney
When: Feb 24, 2009 | 12:00 PM - 1:00 PM