Research DESCRIPTION: We are engaged in materials science and thermal engineering research to control the transport, conversion, and storage of heat, electricity, light, and magnetization in information, energy, and manufacturing technologies. Our research emphasizes fundamental understanding from the macroscale down to the nanoscopic level of quantized energy excitations, including photons, phonons, electrons, and spins. Our approaches include theory-guided synthesis, characterization, and device integration of advanced materials. Our current research efforts are organized along the following three directions: Heterogeneous Integration of Emerging Electronic and Thermal Management Materials The electrical energy consumption by semiconductor devices are converted into high-density heating that causes local hot spots and degrades the device performance and thermomechanical reliability. Based on a recent Semiconductor Research Corporation (SRC) report entitled Rebooting the IT Revolution, the energy required for computing at the current benchmark would exceed the world’s energy production by 2040. The report sets a target of three orders of magnitude reduction in the energy consumption for computing a data bit. This target does not exceed the fundamental limit, but will require innovation and implementation of much more energy-efficient electronic materials, devices, and system designs than current-generation technologies. Along this direction, our research group has advanced the science and engineering of ultrahigh thermal conductivity materials, including carbon nanotubes (CNTs), graphene, hexagonal (h-) and cubic (c-) boron nitride (BN), cubic boron arsenide (c-BAs), and theta-phase tantalum nitride (theta-TaN). We are working actively on heterogeneous integration of c-BAs with lattice-matched III-nitride semiconductors for enhanced electronic and thermal performances. In addition, we investigate field-tunable electronic, thermal, optical, and magnetic properties of two-dimensional (2D) and one-dimensional (1D) materials and pursue heterogeneous integration of these low-dimensional materials into chiplets. Thermal Science and Engineering of Quantum Materials and Hardware As semiconductor devices are advancing toward their theoretical limits, progresses are being made to store information in quantum two-level systems to enable secured quantum communication, highly responsive quantum sensing, and quantum computation of complex problems. Among the various grand challenges that need to be overcome for the establishment and deployment of these quantum information technologies, innovative thermal science and engineering solutions with minimum consumption of rare helium isotopes are required for cooling the quantum hardware to an extremely low temperature to prevent thermal smearing of the small energy spacing of the two-level systems. Meanwhile, thermal measurements can provide unique probes of exotic quantum materials that may provide unanticipated changes in direction in quantum hardware design, which are also being explored with the use of coherent excitations of vibrational and spin waves. One of our current research efforts is focused on modeling and measurement of thermal transport properties and non-equilibrium distributions of temperatures of different quantized energy carriers in the various materials and interfaces of superconducting quantum circuits. Thermalization of superconducting qubits in a dilution refrigerator impacts coherence times and gate fidelity. We aim to advance the frontier in measurements and theoretical computation of quantum hardware thermalization beyond the current practice that relies on phenomenological expression of the electron-phonon and phonon-phonon coupling parameters. In addition, we are investigating new routes to achieve rapid, large, and reversible electronic switching of heat transport in solids and to lay the groundwork for practical thermal switching devices. Thermal switches based on mechanical actuation or fluid flows are essential components in magnetocaloric and electrocaloric refrigeration cycles. Successful experimental demonstration of high-performance solid-state thermal switching devices can impact a range of technologies, including transformative methods based on exciton condensates for helium-free cryogenic cooling of quantum hardware. Moreover, the basic research in topologically controlled correlated electron and spin physics may lead to enhanced qubits. Thermal Materials for Decarbonization of Heat and Fuel A broad spectrum of emerging energy decarbonization technologies requires materials with extraordinary thermal properties at extreme conditions that are often near a structural phase transition. Metallic and ceramic materials with ultrahigh thermal conductivity (k), high phase transition temperatures, high corrosion resistances, and high mechanical strength are indispensable for the manufacturing of efficient high-temperature and high-pressure heat exchangers and heat pumps for decarbonization of industrial heating and enhanced geothermal processes. Meanwhile, long-duration storage of high-temperature heat requires not only high-energy density thermal storage materials, but also high-k materials for rapid charging and discharging of the thermal storage medium and low-k materials for thermal insulation. Ultralow-k thermal insulation materials are also needed to minimize boil off losses in cryogenic storage of liquid hydrogen fuel for hydrogen-fueled vehicle platforms, portable hydrogen powers, and high-volume hydrogen delivery. Moreover, high-temperature and low-k thermal barrier and fire-protection coating materials are critical components for both industrial heating with hydrogen fuel and prevention of battery fires. Along this direction, we pursue the synthesis, characterization, and thermal transport measurements of theoretically predicted bulk and coating materials with potentially extraordinary thermal behaviors at extreme conditions. These experimental efforts are in close collaboration with theoretical investigations of high-order phonon scattering and electron-phonon scattering in first principles Peierls-Boltzmann transport equation prediction of high-k ceramics, metals, and semimetals. Meanwhile, we aim to advance the theoretical and experimental capabilities for improved prediction of lower bounds to k and search of ultralow k in complex and disordered-ordered materials structures. PROJECTS: Heterogeneous Integration and Thermal Characterization of Diamond Films Post-doctoral Researcher: Dr. Janghan Park Collaboration: Profs. Pulickel Ajayan (Rice), Rui Huang (UT Austin) Sponsor: Texas Institute for Electronics Period: 06/2025-06/2027 High-thermal Conductivity Metallic Compounds for Industrial Heat Decarbonization Post-doctoral and Graduate Student Researchers: Dr. Hongzi Li, Yudan Li, Sungyeb Jung Collaboration: Prof. Feliciano Giustino, Prof. Jianshi Zhou Sponsor: Department of Energy Office of Energy Efficiency and Renewable Energy Period: 07/2024-06/2027 EAGER: CET: Nanolattice Materials with Ultra-Low Thermal Conductivity for Decarbonization of Heat and Fuel Graduate Student Researcher: Peter Sokalski Collaboration: Prof. Chih-Hao Chang Sponsor: National Science Foundation Period: 05/2024-04/2026 Quantized Phonon Conductance of One-dimensional Systems Post-doctoral and Graduate Student Researchers: Dr. Yujie Quan, Dr. Xun Li Sponsor: National Science Foundation Period: 04/2024-03/2027 Collaborative Research: FuSe: Heterogeneous Integration of III-Nitride and Boron Arsenide for Enhanced Thermal and Electronic Performance Post-doctoral and Graduate Student Researchers: Dr. Devika Mehta, Woongchul Choi Collaboration: Prof. Xiuling Li (UT-Austin), Bing Lv (UT-Dallas), Emmanouil Kioupakis (Michigan), Siddharth Rajan (Ohio State University) Sponsor: National Science Foundation Period: 10/2023-09/2026 Collaborative Research: Thermal Transport via Four-Phonon and Exciton-Phonon Interactions in Layered Electronic and Optoelectronic Materials Graduate Student Researcher: Chuting Cai, Peter Sokalski Collaboration: Prof. Xiulin Ruan (Purdue University) Sponsor: National Science Foundation Period: 09/2023-08/2026 Thermalization of Microwave Components for Improved Qubit Coherence Post-doctoral and Graduate Student Researcher: Dr. Xun Li, Dr. Yujie Quan Collaboration: Prof. Shyam Shankar Sponsor: Army Research Office Period: 07/2023-06/2027 Manufacturing of High-Strength Nanolattice Coating for Cryogenic Liquid Hydrogen Fuel Storage Graduate Student Researchers: Peter Sokalski Collaboration: Prof. Chih-Hao Chang Sponsor: The University of Texas at Austin Energy Institute Period: 05/2023-05/2024 Tunable Resonant Columbic Heat Transport between Moiré Superstructures Graduate Student Researcher: Devika Mehta Sponsor: Office of Naval Research Period: 06/2022-05/2023 Materials with Extreme Phononic Coupling Graduate Student Researchers: Hwijong Lee, Chuting Cai Collaboration: Profs. Feliciano Giustino, Jianshi Zhou Sponsor: NSF MRSEC Center for Dynamics and Control of Materials Period: 09/2021-08/2023 Extraordinary Electronic Switching of Thermal Transport Graduate Student Researchers: Devika Mehta, Emma Peavler, Chuting Cai, Yajie Huang Collaboration: Profs. Joshua Goldberger, Joseph Heremans, David Johnson, Phillip Kim, Allan MacDonald, Arun Majumdar Sponsor: Office of Naval Research MURI Period: 06/2021-06/2026 Nanofabrication, Modeling, and Characterization of Nano-mechanical/phononic/photonic Devices Post-doctoral Researcher: Dr. Brandon Smith Collaboration: Dr. Matt Eichenfield Sponsor: Sandia National Laboratories Period: 11/2020-06/2021 High-Order Phonon Scattering and Highly Nonequilibrium Carrier Transport in Two-dimensional Electronic and Optoelectronic Materials Graduate and Undergraduate Student Researchers: Peter Sokalski, Rodolfo Cantu Collaboration: Prof. Xiulin Ruan (Purdue University) Sponsor: National Science Foundation Period: 07/2020-09/2023 Collective Energy Transport of Excitons in Two-dimensional Materials Graduate Student Researcher: Yajie Huang Collaboration: Prof. Steve Cronin (USC) Sponsor: Department of Energy Office of Science Period: 06/2019-05/2022 Magnetism and Spin/Heat Coupling in Moiré Superstructures Post-doctoral & Graduate Student Researchers: Devika Mehta, Dr. Sean Sullivan, Dr. Xi Chen Collaboration: Profs. Allan MacDonald, Emanuel Tutuc, Roberto Meyers, Joseph Heremans Sponsor: Army Research Office Period: 09/2018-09/2019 Hydrodynamic Thermal Transport in Graphitic Materials Graduate Student Researchers: Eric Ou, Sean Sullivan, Jihoon Jeong Collaboration: Prof. Yaguo Wang, Prof. Sangyeop Lee (University of Pittsburgh) Sponsor: National Science Foundation Period: 08/2017-07/2020 Innovative Processes for Fabricating Three-Dimensional Ultrathin Foams with Enhanced Thermal Properties Graduate Student Researchers: Evan Fleming, Sally Jia Collaboration: Prof. Donglei Fan Sponsor: National Science Foundation Period: 09/2016-08/2019 Energy Carrier Transport in Functionalized Two-Dimensional Layered Chalcogenides Graduate Student and Post-doctoral Researchers: Hwijong Lee, Dr. Mir Mohammad Sadeghi Collaboration: Prof. Steve Cronin (USC) Sponsor: Department of Energy Office of Science Period: 06/2016-05/2019 Ultrahigh Thermal Conductivity Materials Graduate Student and Post-doctoral Researchers: Yuanyuan Zhou, Hwijong Lee, Dr. Jaehyun Kim, Dr. Xi Chen, Dr. Sean Sullivan Collaboration: Profs. David Broido (Boston College), David Cahill & Pinshane Huang (UIUC), Gang Chen (MIT), Ni Ni (UCLA), Zhifeng Ren (University of Houston), Bing Lv (University of Texas at Dallas), Jianshi Zhou (UT Austin) Sponsor: Office of Naval Research MURI Program Period: 06/2016-10/2021 Graphitic Coatings and Porous Networks for Vehicle Thermal Management Graduate Student and Post-doctoral Researchers: Evan Fleming, Dr. Iskandar Kholmanov Sponsor: Toyota Motor Corporation Period: 04/2016-03/2017 Probing Thermal Transport in Three-Dimensional Pillared Graphene Structures Graduate Student and Post-doctoral Researchers: Evan Fleming, Dr. Iskandar Kholmanov Collaboration: Profs. Liming Dai (CWRU), Dr. Xiulin Ruan (Purdue), Dr. Ajit Roy (ARFL) Sponsor: Airforce Office of Scientific Research MURI/Case Western Reserve University Period: 09/2015-11/2017 EFRI 2-DARE: Enhancing Electronic and Thermal Properties in Epitopotaxial Ge/Sn Graphane Heterostructures Graduate Student Researcher: Gabriella Coloyan, Devika Mehta Collaboration: Profs. Joshua Goldberger (OSU), David Broido (Boston College), David Cahill (UIUC), Joseph Heremans (OSU) Sponsor: National Science Foundation Period: 09/2014-03/2020 Development of Light Scattering Characterization Equipment for the Study of Magnon and Phonon Dynamics in Materials with Spin/Heat Coupling Collaboration: Prof. Elaine Li (UT Austin) Sponsor: Army Research Office Defense University Research Instrumentation Program (DURIP) Period: 06/2014-06/2015 Size-dependent Phonon Transport in Boron Arsenide with Potentially Record-high Thermal Conductivity Post-doctoral & Graduate Student Researchers: JaeHyun Kim, Dan Evans, Owen Williams, Dr. Dan Sellan Collaboration: Prof. Alan Cowley (UT Austin) Sponsor: Office of Naval Research Period: 06/2014-09/2017 Fully Integrated 2D Nanomaterials for High-Performance Flexible Nanoelectronics Graduate Student Researcher: Brandon Smith Collaboration: Prof. Deji Akinwande (UT Austin) Sponsor: Office of Naval Research Period: 01/2014-12/2017 Probing Highly Non-equilibrium Thermal Transport in Nanostructures and Devices Graduate Student Researchers: Kevin Olsson, Sean Sullivan, Annie Weathers Collaboration: Prof. Elaine Li (UT Austin) Sponsor: National Science Foundation Period: 09/2013-08/2017 Materials with Extraordinary Spin/Heat Coupling Post-doctoral & Graduate Student Researchers: Dr. Annie Weathers, Dr. Xi Chen, Sean Sullivan, Dr. Kyongmo An Collaboration: Profs. Roberto Meyers, Joseph Heremans (Ohio State University), David Cahill (UIUC), David Awschalom (Univ of Chicago), Yaroslav Tserkovnyak (UCLA), Elaine Li (UT Austin), Jianshi Zhou (UT Austin) Sponsor: Army Research Office Multidisciplinary Uiversity Research Intitiative (MURI) Period: 12/2013-09/2019 Phonon and Electron Transport in Pristine Two-Dimensional Layered Nanostructures and Heterostructures Graduate Student Researchers: Gabriella Coloyan, Eric Ou Collaboration: Prof. Steve Cronin (USC) Sponsor: Department of Energy Office of Basic Energy Science Period: 06/2013-05/2016 NSF Nanosystems Engineering Research Center: Nanomanufacturing Systems for Mobile Computing and Devices (NASCENT) Graduate Student Researchers: Qianyu (Sally) Jia, Brandon Smith, Gabriella Coloyan, David Choi, Mir Mohammad Sadeghi Collaboration: Profs. Deji Akinwande, Jayathi Murthy Sponsor: National Science Foundation Period: 09/2012-08/2020 MRI: Acquisition of a Spark Plasma Sintering System for Engineering Advanced Energy Materials and Materials Science Education Collaboration: Profs. Jianshi Zhou, John Goodenough, Arumugam Manthiram, Desiderio Kovar (UT Austin) Sponsor: National Science Foundation Period: 09/2012-06/2015 Thermal Batteries for Electric Vehicles Post-doctoral & Graduate Student Researchers: Evan Fleming, Dr. Hengxing Ji, Dr. Abhijit Paul, Dr. Daniel Sellan, Dr. Shaoyi Wen, Dr. Eunsu Paek, Dr. Iskandar Kholmanov Collaboration: Profs. Chris Bielawski, Alex da Silva, Rodney S. Ruoff, Jayathi Murthy, Gyeong Hwang, Dr. Peng Zhou, Dr. Dolf van der Heide Sponsor: Department of Energy ARPA-E Period: 11/2011-6/2015 Topological Insulator Coherent Energy Devices Post-doctoral and Graduate Student Researchers: Dr. Michael Pettes, JaeHyun Kim Sponsor: Defense Advanced Research Project Agency (DARPA) / Purdue University Period: 06/2011-06/2015 High-Performance Thermoelectric Devices based on Abundant Silicide Materials for Vehicle Waste Heat Recovery Graduate Student Researchers: Chad Baker, Xi Chen, Haiyan Fateh, Daniel Salta, Libin Zhang Collaboration: Profs. J. B. Goodenough, M. J. Hall, J. S. Zhou (UT Austin), J. Song (University of Wisconsin-Madison) Sponsor: National Science Foundation & Department of Energy Joint Thermoelectric Partnership Period: 10/2010-05/2015 Energy Transport in Graphene Graduate Student Researchers: Michael T. Pettes, Insun Jo, Mir Mohammad Sadeghi, Gabbi Coloyan Collaboration: Prof. Steve Cronin (USC) Sponsor: Department of Energy Office of Basic Energy Science Period: 06/2010-05/2013 Ballistic and Quantum Thermal Transport Phenomena and Devices Postdoctoral and Graduate Researchers: Dr. Jae Hun Seol, Dr. Arden Moore, JaeHyun Kim, Eric Ou Sponsor: Office of Naval Research Period: 02/2010-01/2013 High-Throughput Nanoimprint Fabrication of Shape-Specific, Stimuli-responsive Polymeric Nanocarriers for Drug and Imaging Agent Delivery Graduate Student Researchers: Mary C. Moore, Vikramajit Singh, Patrick Jurney, Rachit Agarwal, Scott Marshall, David Choi Collaboration: Prof. S.V. Sreenivasan (UT Austin), Prof. K. Roy (UT Austin), Dr. D. LaBrake (Molecular Imprint, Inc) Sponsors: National Science Foundation Period: 07/2009-09/2013 Electronic Thermal Transport in Nanoscale Conductors Graduate Student Researchers: Mir Mohammad Sadeghi, Jae Hun Seol, Annie Weathers Sponsor: National Science Foundation Period: 07/2009-06/2013 Characterization of Nanostructured Thermoelectric Materials Post-doctoral & Graduate Researchers: Dr. Arden Moore, Dr. Huijun Kong, Dr. Yong Lee, Dr. Michael Pettes, JaeHyun Kim Sponsor: Office of Naval Research Period: 07/2008-09/2011 Shape Specific, Enzyme-Responsive, Nano-Imprinted Particles for Drug Delivery Graduate Student Researchers: Mary C. Moore, Rachit Agarwal, JaeHyun Kim Collaboration: Prof. K. Roy (UT Austin) Sponsors: National Institute of Health Period: 07/2008-06/2011 Batch-Fabricated Nanowire Plasmonic Probes for Near Field Imaging of Single Molecules and Cells Graduate Student Researcher: JaeHyun Kim Post-doctoral Researcher: Dr. Yong Lee Sponsor: Texas Higher Education Coordinating Board Norman Hackerman Advanced Research Program Period: 05/2008-05/2010 Structure-Optical-Thermal Relationships of Carbon Nanotubes Graduate Student Researchers: Michael T. Pettes, JaeHyun Kim Collaboration: Prof. Steve Cronin (USC) Sponsor: Department of Energy Office of Basic Energy Science Period: 06/2007-05/2010 Catalyst Substrates with Nanoscale Features for Enhanced Reaction Activity Graduate Student Researcher: Chad Baker Collaboration: Prof. M. J. Hall (UT Austin) Sponsor: Texas Hazardous Waste Research Center Period: 09/2007-08/2010 High Temperature and Magnet Cryostats for Characterization of Nanowire and Thin Film Thermoelectric Materials Sponsor: Office of Naval Research Period: 05/2007-09/2008 Thermal Transport at Nanoscale Point and Line Constrictions and Interfaces Graduate Student Researchers: Jae Hun Seol, Arden L. Moore, Nathan Malcolm, Sanjoy Saha Collaboration: Prof. John R. Howell (UT Austin), Dr. Ravi S. Prasher (Intel) Sponsor: National Science Foundation Period: 09/2006-08/2010 NER: Nanoimprint Fabrication of Stimuli-responsive Drug Delivery Carriers Graduate Student Researchers: Luz Cristal Glanchai, Mary C. Moore Collaboration: Prof. K. Roy (UT Austin) Sponsors: National Science Foundation Period: 08/2006-07/2007 Room-Temperature Scanning Single-Electron-Transistor Microscopy of Nanoelectronic Devices Gradate Student Researcher: Michael T. Pettes Post-doctoral Researcher: Dr. Yong Lee Collaboration: Prof. Zhen Yao (UT Austin) Sponsor: Texas Higher Education Coordinating Board Norman Hackerman Advanced Research Program Period: 08/2006-07/2008 Nanowire Composite Peltier Coolers Graduate Student Researcher: Arden L. Moore Sponsor: DARPA Advanced Processing and Prototyping Center (AP2C) Period: 11/2005-11/2006 Investigation of Electrical Conductivity of Silicide and Copper Nanowires Gradate Student Researcher: Bin Li Collaboration: Prof. Paul S. Ho (UT Austin) Sponsor: National Institute of Standards & Technology Period: 06/2005-05/2006 Nanowire Composites for Energy Efficient Thermoelectric Refrigeration and Power Generation in Space Applications Graduate Student Researchers: Feng Zhou, Jae Hun Seol Collaborations: Dr. Laura Ye, Dr. Natalio Mingo, NASA Ames Research Center Sponsor: NASA through Eloret Corporation Period: 05/2005-05/2007 Directed Assembly of Metal Oxide Nanowires with Microsystems for Sensor Applications Graduate Student Researcher: Choongho Yu Collaboration: Prof. Z. L. Wang (Georgia Institute of Technology) Sponsor: UT Research Grant Program Period: 09/2004-08/2005 Novel Nano and Micro-fabrication Methods for Injectable, Tissue-targeted, Stimuli-responsive Delivery Vehicles: Towards Simultaneous Delivery of Therapeutics and Contrast-agents Graduate Student Researchers: Luz Cristal Glanchai, Mary C. Moore Collaboration: Prof. K. Roy (UT Austin) Sponsors: Charles W. Tate & Judy Spence Tate Charitable Foundation through UT Center for Biomedical Engineering Period: 09/2004-08/2005 Nanoconductors for Future Interconnects and Air Bridge Interconnects Graduate Student Researcher: Bin Li, Anastassios Mavrokefalos Collaboration: Prof. Paul S. Ho, Zhen Yao, Rui Huang (UT Austin) Sponsor: SEMATECH Period: 09/2004-08/2006 YIP: Characterization of Nanostructures for Efficient Thermoelectric Refrigeration and Power Generation Graduate Student Researchers: Anastassios Mavrokefalos, Feng Zhou Sponsor: Office of Naval Research Period: 06/2004-09/2008 Compact General-Purpose Bioagent Detector Collaboration: Prof. Peter Gascoyne (UT MD Anderson Cancer Center), Prof. Shaochen Chen (UT Austin) Sponsor: DOD Space and Naval Warfare Center Period: 07/2003-06/2004 CAREER: Thermal Transport and Thermoelectric Measurements of Nanotransistors, Nanowires, and Superlattices Graduate Student Researchers: Choongho Yu, Jianhua Zhou, Sanjoy Saha, Michael T. Pettes, Jae Hun Seol Sponsor: National Science Foundation Period: 03/2003-02/2008 Micro-flow Cytometers based on Dielectrophoretic Particle Focusing Graduate Student Researcher: Choongho Yu Collaboration: Prof. Peter Gascoyne (UT MD Anderson Cancer Center) Sponsor: Whitaker Foundation through UT Center for Biomedical Engineering Period: 09/2002-06/2003 Acquisition of a Scanning Probe Microscope and a Liquid Helium Cryostat for Nanoscale Thermal Science Research and Education at the University of Texas at Austin Collaboration: Profs. Shaochen Chen and Zhen Yao (UT Austin) Sponsor: National Science Foundation Period: 06/2002-07/2004
