Achieving Ultra-High Thermal Conductivity in Cubic BAs Through Synergistic Impurity Control, Advanced Growth Techniques, and Rapid Non-Destructive Characterization

About This Grant

Nontechnical Summary Cubic boron arsenide holds exceptional promise for next-generation electronics with its unique pairing of ultrahigh thermal conductivity and high charge-carrier mobility. Compared to silicon, the bedrock of modern microelectronics, it delivers carrier mobility three times greater and thermal conductivity ten times higher. Transistors built from or integrated with cubic boron arsenide therefore switch faster and run cooler, directly addressing the heat-dissipation limits of silicon devices. Yet critical challenges persist such as controlling trace impurities, achieving reproducible n-type and p-type doping, and growing large, uniform single crystals. This research tackles those challenges head-on through an innovative growth technique that ensures high crystal quality and purity while enabling controlled dopiong. The research is integrated with semiconductor education and workforce development. The principal investigator embeds the project in the Graduate Certificate in Semiconductor Engineering and Manufacturing, supported by the Next-generation Microelectronics Manufacturing initiative. Students will experience hands-on materials engineering and device fabrication. Findings feed into undergraduate and graduate courses via the Nano Engineering Minor Option. Outreach through the Texas Center for Superconductivity and the Cullen College of Engineering via laboratory tours, technical lectures, and live demonstrations to engage learners from kindergarten through grade twelve as well as undergraduates and graduate students. Participation in the Research Experiences for Undergraduates program further broadens access to cutting-edge semiconductor research. Technical Summary The research team synthesizes uniform, high-quality crystals with controlled electrical properties by combining modified chemical vapor transport and flux-growth methods with ion implantation, thermal annealing, and laser float-zone refining. Raman scattering, low-temperature photoluminescence, and time-of-flight secondary-ion mass spectrometry identify and quantify impurities and dopants. A novel nanosecond time-domain thermoreflectance technique operating without a metal transducer provides rapid, noninvasive thermal-conductivity mapping. Crystals that exhibit ultrahigh conductivity undergo transient-reflectance carrier-diffusion measurements to set new mobility benchmarks. This integrated approach advances fundamental insight into phonon transport, impurity interactions, and dopant behavior in wide-bandgap semiconductors, laying the groundwork for future high-performance electronic materials manufacturing. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.