Abstract: In oxide semiconductors, atomic-scale native defects such as vacancies and interstitial atoms affect the performance of devices such as photocatalysts, sensors, and optoelectronics. It is helpful to have the ability to control the type, concentration, and spatial distribution of such species, also known as ​“defect engineering.” My research has provided new insights for atomic-scale defects in semiconducting oxides for determination of atomic-scale geometric and electronic structure and for estimation of activation barriers as well as pre-exponential factors for kinetic rate expression.

In this talk, I will discuss a concept for manipulating atomic-scale defects in semiconducting oxides involving exposure to O₂ gas, focusing on oxygen-related defects in rutile TiO₂. I established the diffusion mechanisms by which this approach works by integrating experiments with first-principles DFT calculations. I will also discuss a computational integration process by DFT calculations and mesoscale microkinetic modeling for determination of rate constants for exchange of oxygen-related defect on (110) surface of rutile TiO₂, where I demonstrated dependence of Fermi level on thermodynamic and kinetic energy landscape.

Bio: Heonjae Jeong is a Ph.D. candidate in mechanical engineering at the University of Illinois at Urbana-Champaign.