Past Event: Babuška Forum

How to use quantum mechanics to make better semiconductors

Feliciano Giustino, Professor, Department of Physics, Oden Institute, UT Austin

Abstract

One of the fundamental properties of semiconductors is their ability to support electric currents in the presence of electric fields (drift) or carrier concentration gradients (diffusion). These properties are described by transport coefficients such as electron and hole mobilities and diffusion coefficients. During the past decade, there has been considerable progress in quantum-mechanical calculations of carrier transport combining the Boltzmann transport equation with density functional theory. The reliability and accuracy of these calculations are improving at a fast pace, and the first applications of these recent developments in device engineering are emerging [1,2]. Within this context, I will review the formalism leading to the Boltzmann transport equation, and discuss the key approximations underlying this approach. I will describe recent algorithmic implementations, including the software package EPW [3], and discuss the computational challenges associated with quantum-mechanical calculations of transport properties. I will illustrate these concepts using recent calculations on standard semiconductors such as silicon [4], photovoltaic materials such as lead halide perovskites [5], and semiconductors for power electronics such as gallium nitride [7] and gallium oxide. I will conclude by discussing outstanding challenges and promising avenues for future research. [1] S. Poncé, W. Li, S. Reichardt, F. Giustino, Rep. Prog. Phys. 83, 36501 (2020). [2] F. Giustino, Rev. Mod. Phys. 89, 015003 (2017). [3] S. Poncé, E. R. Margine, C. Verdi F. Giustino, Comput. Phys. Commun. 209, 116 (2016). [4] S. Poncé, E. R. Margine, F. Giustino, Phys. Rev. B(R) 97, 121201 (2018). [5] S. Poncé, M. Schlipf, and F. Giustino, ACS Energy Lett. 4, 456 (2019). [6] S. Poncé, D. Jena, and F. Giustino, Phys. Rev. Lett. 123, 096602 (2019). BIO Feliciano Giustino holds the Moncrief Chair in Quantum Materials Engineering and is Professor of Physics at the University of Texas, Austin. He earned his Ph.D. in Physics at the Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland, and held a post-doctoral appointment at the University of California, Berkeley. Prior to joining the University of Texas he spent over a decade at the University of Oxford as Professor of Materials Science, and one year at Cornell University as the Mary Shepard B. Upson Visiting Professor in Engineering. He is a Clarivate Analytics' Highly Cited researcher, the recipient of a Leverhulme Research Leadership Award, and a Fellow of the American Physical Society. Giustino specializes in electronic structure theory, high-performance computing, and the atomic-scale design of advanced materials using quantum mechanics. He is author of 140+ scientific publications and one book on density-functional theory. He initiated the open-source software project EPW for ab initio calculations of electron-phonon interactions, which is regularly used by research groups around the world. (The Babuška Forum series was started by Professor Ivo Babuška several years ago to expose students to interesting and curious topics relevant to computational engineering and science with technical content at the graduate student level (i.e. the focus of the lectures is on main ideas with some technical content). Seminar credit is given to those students who attend.)