Department of Materials Science and Engineering Spring Seminar Series: Emmanouil Kioupakis

Description

Emmanouil Kioupakis, a professor of materials science and engineering and of applied physics at the University of Michigan, will give a talk titled "Computational Characterization and Discovery of Semiconductors and High-Entropy Materials Through First-Principles Calculations of Defect Properties" as part of the Department of Materials Science and Engineering Spring Seminar Series.

Abstract:

Defects and dopants play a crucial role in the operation of semiconductor devices: dopants provide the charge carriers that conduct electricity, while mid-gap states generated by defects can cause leakage in dielectrics. Understanding the atomic structure and electronic properties of defects is essential for the development of new materials with targeted properties that surpass the current state of the art in device technology. Recent advances in methodologies, software, and high-performance computing have enabled first-principles calculations for realistic defects in materials that can accelerate the development of new compounds with superior properties.

In this talk, I will discuss how atomistic calculations enhance our understanding of defects and dopants in semiconductors and electronic oxides. I will present insights obtained from atomistic calculations on the inherent limitations of Ga2O3 as an ultra-wide-band-gap semiconductor in power-electronic applications. In contrast, I will showcase our recent discovery of rutile GeO2 as a superior alternative material with higher electrical and thermal conductivity and ambipolar dopability, which can potentially outperform all current ultra-wide-band-gap technologies. Furthermore, I will present our research on defects in high-entropy oxides, which has led to the identification of local composition motifs that can predict the likelihood of defect formation. In addition, I will present our discovery of a new class of high-entropy chalcogenide semiconductors that are stabilized by the configurational entropy of both the cation and the anion sublattices and that exhibit ambipolar dopability. Our work exemplifies the substantial impact of predictive atomistic calculations in modern materials science research, paving the way for the development of electronic materials with targeted properties.