MSE Seminar: Derek Miller, Advancing electronic structure characterization of semiconducting oxide nano-heterostructures for gas sensing

Abstract

The most promising recent advances in resistive-type gas sensors have come from semiconducting oxide nano-heterostructures which incorporate two or more sensor materials on the nano-scale in either core-shell, decorated nanowire or hierarchical structures. Rapid progress in new synthesis routes has made it possible to engineer and optimize specific types of nano-heterostructures for a given application but a lack of fundamental understanding of the mechanisms of these heterostructures limits progress in nano-heterostructure design. Several proposed methods to understand and characterize these structures will be discussed, as well as current problems and pitfalls that need overcome or avoided. One method is to fabricate single-nanowire sensors to obtain electrical measurements precisely knowing the geometry of the tested material without the confounding variables of inter-particle junctions and variations in particle size and morphology. The electronic structure of these materials can also be probed using high-spatial resolution (<5 nm) techniques in a STEM microscope such as valence-loss EELS and STEM-cathodoluminescence. These techniques provide valuable information on the band gap and defect states of individual nanowires and nanoparticle coatings that have implications not only for gas sensors, but also in photocatalysis, optoelectronics, and semiconductor defect quality control.

Bio

Derek graduated from Michigan State University in MSE in 2011, also completing three internships at NASA Glenn Research Center before starting at Ohio State. His initial graduate work focused on ultra-porous oxide aerogel materials on an NSF Fellowship, but later shifted toward semiconducting oxide nano-heterostructures in 2013 when he received a NASA NSTRF fellowship. When asked about examples of efficiently working as a team with colleagues, Derek credits these leadership and teamwork experiences with landing him a job at Cree in Raleigh, North Carolina in R&D of LED components, which he starts in April. 

Derek’s greatest accomplishment in graduate school was being the captain of an all-grad MSE student team which won the overall Ohio State IM Dodgeball Championship in 2015. This trophy shirt fits nicely in his trophy shirt case alongside an IM Pickleball Tournament champion and several bar-league sand volleyball championships where MSE/WE grad students played crucial roles. He also enjoys making friends but mostly enemies while playing cornhole at MSE happy hours. Derek also recently completed a circumnavigation of the world visiting eight countries, but will have to put more intercontinental travel plans on hold now that he is entering the real world of rigid work days and limited vacation. His parting advice is “Stay in school, stay as long as you can - cherish it.”