(14d) Thin Films and Two-Dimensional Materials for Energy Applications

Research Interests:

New materials are constantly being designed to meet the growing and changing needs of society, such as energy storage, batteries, and electronic devices. Computers are now powerful enough that screening studies are practical, allowing us to do quick tests on a huge variety of materials. I have used density functional theory (DFT) to calculate important electrical and mechanical properties of these systems. Of special interest to me are two-dimensional materials, and interfaces between materials; interfaces allow fascinating phenomena such as two-dimensional conducting gases, and two-dimensional materials are so thin that their physical properties can be very different than that of bulk materials. In both cases, the properties of the system are vastly different for surfaces/interfaces/two-dimensional materials than their corresponding bulk cases.

Postdoctoral Projects: â??Modeling of two-dimensional transitional metal carbonitrides (MXenes) for catalysis and energy storageâ?

Under supervision of Jens Nørskov and Aleksandra Vojvodic, Department of Chemical Engineering, Stanford University and SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory

PhD Dissertation: â??First-Principles Studies of Perovskite Thin Films and Heterostructuresâ?

Under supervision of Alexander Demkov, Department of Physics, the University of Texas at Austin

Research Experience:

My academic career bridges physics, chemistry, materials science, and chemical engineering. I have always worked with experimentalists; I was fortunate in that my PhD group was dual theory/experimental. I have experience modeling mechanical, electric, magnetic and optical properties using DFT. I have had experience with multiple high-performance clusters, from massive nationwide level computer centers (TACC at the University of Texas at Austin, NERSC at Lawrence Berkeley National Laboratory) to midsize (Sherlock cluster at Stanford University) to a small cluster used exclusively by our research group (SUNCAT cluster at SLAC).

Teaching Interests:

I taught for four semesters at UT Austin; I taught a lab for premedical students taking physics, with multiple office hours per week to help students and encourage their learning, specially the application of physics towards medicine. UT Austin also gave opportunities to â??coachâ?? students, i.e. a general area where students from any class, at any level, could come and ask questions about physics, which I also participated in for four semesters. I tutored pro bonoat my undergraduate and also taught on the side as a graduate student (from high school level to college physics).

Future Direction: 

As faculty, I want to continue my research on both MXenes. These fascinating materials show vastly different mechanical and electrical properties that vary with functionalization. I would like to collaborate with experimentalists to show how their properties can be affected by different functionalizations, and demonstrated in the lab. I also want to understand better how to control the functionalization through experimental means (strain, temperature, pH, etc.) I also want to apply screening studies to interfaces (doping, interstitial atoms, vacancies), in order to model interfaces in practical devices such as field effect transistors, spin filters, and semiconducting heterojunctions. Because MXenes are so thin, they have interesting potential in device applications, and they are perfect for screening studies, because a small change in the composition can have drastic effects on conductivity, tensile strength, etc. The logical next step is to understand how their properties are affected by deposition/growth on real substrates.

Selected Publications:

â??Two-Dimensional Transition Metal Carbides (MXene) as Efficient Electrocatalysts for Hydrogen Evolutionâ?, K.D. Fredrickson, Z.W. Seh, B. Anasori, J. Kibsgaard, A.L. Strickler, M.R. Lukatskaya, Y. Gogotsi, T.F. Jaramillo and A. Vojvjodic, submitted to ACS Energy Letters, 2016

A.A. Demkov, K.J. Kormondy and K.D. Fredrickson, "Two-Dimensional Electron Gas at Oxide Interfaces," in Oxide Materials at the Two Dimensional Limit, ed. F. Netzer and A. Fortunelli (Springer, New York) 2016doi: 10.1007/978-3-319-28332-6

â??Spin-polarized, orbital-selected hole gas at the EuO/Pt interfaceâ?, K.D. Fredrickson and A.A. Demkov, J. Appl. Phys. 119, 095309 (2016). doi: 10.1063/1.4942837

â??Carrier density modulation in a germanium heterostructure by ferroelectric switchingâ?, P. Ponath, K.D. Fredrickson, A.B. Posadas, Y. Ren, X. Wu, R.K. Vasudevan, M.B. Okatan, S. Jesse, T. Aoki, M.R. McCartney, D.J. Smith, S.V. Kalinin, K. Lai and A.A. Demkov, Nat. Commun. 6, 6067 (2015). doi: 10.1038/ncomms7067

â??Atomic and electronic structure of the ferroelectric BaTiO₃/Ge(001) interfaceâ?, K.D. Fredrickson, P. Ponath, A.B. Posadas, M.R. McCartney, T. Aoki, D.J. Smith and A.A. Demkov, Appl. Phys. Lett. 104, 242908 (2014). doi: 10.1063/1.4883883