Bryan M. Wong, PhD, assistant professor, Department of Chemistry, Drexel University
Abstract: The ability to tune electronic properties in nanomaterials holds great promise for incorporating these materials in next-generation transistors, circuits, and nanoscale devices. In particular, the use of predictive first-principles calculations plays a vital role in rationally guiding experimental efforts to optimize energy harvesting in nanoscale and mesoscale materials. In this seminar, I will highlight recent work in my group on low-dimensional 1D nanostructures using first-principles computational methods. First, I will highlight the use of large-scale DFT calculations to understand optical detection mechanisms in a joint experimental-theoretical study of functionalized carbon nanotubes. Finally, a new theoretical approach is presented to understand electron localization effects in heterostructure nanowires. At nanoscale dimensions, the formation of mobile electron gases in AlGaN/GaN core-shell nanowires leads to degenerate quasi-one-dimensional electron localization, in striking contrast to what would be expected from analogy with bulk heterojunctions. The reduction in dimensionality in these nanowires dramatically changes their electronic structure, leading to novel properties such as ballistic transport and conductance quantization. At the end of this seminar, I will give a live demonstration on running this user-friendly nanowire code (publicly available on my homepage) on a laptop computer to illustrate its predictive capabilities.