Seminar: “Using beams to study thin film growth in situ and in real time: from organic small molecule semiconductors to transition metal dichalcogenides” by James Engstrom, Cornell University
The study of thin film growth using real time techniques has always represented an important challenge to the experimentalist. Over the past several years our group has been employing supersonic molecular beam techniques and in situ real time X-ray synchrotron radiation to examine a variety of systems in two important emerging areas: organic small molecule semiconductors and transition metal dichalcogenides (TMDs). In a number of cases we have supplemented the information we obtain from X-ray scattering, with results from in situ real time X-ray fluorescence, and atomic force microscopy. In this presentation we will review some of our more intriguing findings. We will address issues such as: does the sequence of deposition matter concerning the growth of heterostructures involving two small molecule organic semiconductors? do lower growth rates and higher substrate temperatures always produce smoother thin films? and in cases where both a thin-film and bulk phase form, which grows first? The growth of thin films of TMDs has attracted a great deal of interest lately, yet in situ real time studies of these materials are few and far between. We will show that in situ X-ray synchrotron radiation is a powerful probe of the growth of these materials, and we will show for the first time direct, real-time observation of layer-by-layer growth of a TMD 2D semiconductor.
James R. Engstrom is currently a Professor in the School of Chemical and Biomolecular Engineering at Cornell University. Since 2002 he has also been a member of the Graduate Field of Chemistry and Chemical Biology. Prof. Engstrom is the recipient of numerous awards, including, in 1991, a NSF Presidential Young Investigator Award, the Lilly Endowment Teaching Fellowship in 1995, as well as 2 College of Engineering Teaching Awards. In 2005 he was made a Fellow of the American Vacuum Society. From 1998 to 2001, he worked for Symyx Technologies, where he was vice president of high-throughput screening and electronic materials. Presently, Professor Engstrom’s research is focusing in three areas: controlling thin film nucleation in nanoscale electronics using techniques such as atomic layer deposition; organic thin film electronics, using in situ real time X-ray synchrotron radiation; and modification and processing of inorganic nanocrystalline materials. He earned a B.S. degree in chemical engineering from the University of Minnesota and a Ph.D. degree in chemical engineering from the California Institute of Technology.Tags: Engstrom, organic semiconductor, semiconductors, thin film processes, transition metal dichalcogenides, X-ray, X-ray synchrotron radiation