First Principles Studies of Novel Approach for Achieving Ultrahigh Thermal Conductivity in Materials

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CBET-1402949BroidoAs microelectronic devices continue to shrink, heat dissipation is becoming an increasingly critical technology challenge. High thermal conductivity materials are urgently needed to address this challenge. The carbon-based crystals, diamond, graphite, graphene and carbon nanotubes have long been known to have by far the highest thermal conductivities, κ, of any material. Diamond, in particular, is widely used for passive cooling of electronics, but its synthetic fabrication suffers from slow growth rates, high cost, and low quality. In spite of well-defined criteria to guide the search for new high κ materials, little progress has been made over the years. Using an accurate, first principles, theoretical approach, we have recently found that an unexpected material, boron arsenide should have exceptionally high thermal conductivity, comparable to that of diamond. This surprising finding stems from fundamental material properties, some of which are not typically connected to prescriptions for high κ in materials. The objectives of this project will be to study in detail the thermal transport properties of boron arsenide, and to identify new high κ materials using the materials search paradigm identified for boron arsenide. This project will therefore help address the heat dissipation challenge and benefit society by aiding in the development of new high κ materials. This will facilitate technological breakthroughs that may lead to the next generation of passive cooling devices for electronics, such as heat spreaders and heat sinks.This research effort will implement a state-of-the-art, first principles thermal transport approach to provide fundamental understanding of our recent finding of exceptionally high κ in boron arsenide and the proposed new paradigm for achieving high thermal conductivity in materials. A central feature of this approach is that it has no adjustable parameters. Furthermore, it has already demonstrated excellent agreement with measured thermal conductivities for a wide range of materials, validating its predictive capability. Efficient computational algorithms incorporating the novel material properties found in boron arsenide will be used to implement a broad search for a new class of novel high κ materials. This will facilitate the discovery of as yet unidentified high κ materials. Deeper understanding of the role of defects and insight into how to tune the desirable material properties to enhance κ will also be investigated. This project with provide important new insights into the nature of thermal conductivity in materials, give guidance to measurement efforts, and facilitate the design and of high κ materials for thermal management applications.