Removing heat from semiconductor devices such as transistors is one of the primary challenges facing many technologies with high commercial and environmental impact, such as next-generation cell phone networks, electric vehicle power converters, laser diodes, and solid-state lighting. Much of the heat buildup occurs at the interface between the semiconductor device and the substrate material to which it is attached. This project focuses on reducing the resistance to heat flow at this interface by modifying it with nanostructures (i.e. arrays of sub-micron wires and cones) in a way that will allow heat to more easily travel from the semiconductor into the substrate. If successful, this project will result in a reliable method to greatly improve the performance and efficiency of many technologies based on semiconductors. In addition, this research will have an educational impact through the training of graduate and undergraduate students, and through participation in K-12 outreach programs.
The specific research objectives of this proposal are 1) create a scalable and transferrable method to enhance thermal transport across an interface using a novel technique of nanostructuring at the interface; and 2) advance the field of thermal transport by proposing then validating multiscale models of phonon transport across nanostructured interfaces. The research plan describes an approach to rationally design and fabricate arrays of high-aspect-ratio nanostructures on the mating surfaces of two materials and then bond them together in a fault-tolerant approach with a soft wetting metal such as indium. The project focuses on improving thermal transport between wide bandgap semiconductors and high thermal conductivity substrates, with an emphasis on diamond. The interfaces will be measured using thermoreflectance techniques and compared with a multiscale model that incorporates results from first principles calculations for phonon transport in nanostructures into a larger scale continuum model. The results of this project will pave the way for understanding and optimizing interfaces for improved heat transfer between materials with widely different atomic structures and phonon properties.
