Characterization of Semiconductors for Novel Electronic, Photonic, and Energy Applications

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My research program is focused on studying metal oxide semiconductors to advance fundamental science; to streamline identifying promising materials for new applications in electronics, optoelectronics, energy storage, and catalysis; and to predict the performance of novel devices. Metal oxide semiconductors are attractive materials because they are stable and inexpensive, but there are many challenges that must be overcome before these materials can be used in next-generation devices. These challenges relate to understanding the atomic-scale electronic properties of the semiconductor. Tuning the electronic properties of the semiconductor involves adding impurities, removing atoms (creating vacancies), or using nanomaterials - but exactly how these modifications change the electronic properties of the host semiconductor is difficult to determine. Synchrotron-excited X-ray spectroscopy is a rapidly developing technique that provides a bulk and surface sensitive, element-specific, and non-destructive probe of material properties. This research will use soft X-ray spectroscopy (SXS) to characterize materials to assess their suitability for practical applications. These measurements will be supported by ab-initio calculations such as density functional theory (DFT) and standard laboratory characterization techniques. The long-term goal of this research program is to develop a robust joint theoretical and experimental methodology for rapid characterizing novel materials and accurately predicting of their influence on device performance. This long-term goal is to be pursued along three research themes: the influence of defects on the electronic properties of metal oxide semiconductors (Theme 1), controlling the electronic properties of metal oxide semiconductors with doping (Theme 2), and interfaces and heterojunctions of metal oxide semiconductors (Theme 3). A highlight of this research program is using non-destructive methods to characterize trace amounts of a new material or a prototype device, and to connect fundamental material properties to device performance. A systematic study of novel and alternative semiconductors increases fundamental knowledge in materials science, will providing valuable insight into potential uses of these semiconductors in practical applications and commercial devices. Although there is increasing investment in synchrotrons, use of these facilities for applied and quantitative characterization of electronic materials is lacking. An analysis framework for rapid and accurate characterization of device-relevant parameters from synchrotron techniques will address this deficiency and increase the utility of synchrotron-excited X-ray spectroscopy as a new standard tool for the electronics, photonics, and battery industries. This increases the efficiency of broad searches across novel materials for those best suited for next generation technologies and shortens development time before commercialization.