Best poster award for collaborative research effort

Yingying Zhang, who is pursuing her doctoral degree in mechanical engineering, won best poster award at the the 2021 Materials Research Society Fall Meeting in Boston. Zhang's poster is titled “Thickness-Dependent Thermal Conductivity of Mechanically Exfoliated β˗Ga2O3Thin Films,” and was presented in Symposium EN03-Thermal Materials, Modeling and Technoeconomic Impacts for Thermal Management and Energy Application. She is working on her doctoral research under the guidance of professor Xiaojia Wang in the Department of Mechanical Engineering (ME).   

The poster is the outcome of a collaborative effort between two research groups, one led by Russell J. Penrose Professor of Nanotechnology Steven Koester of ECE and the other by Wang of ME. The collaboration focuses on the thermal properties of beta-phase gallium oxide (β˗Ga2O3) bulk crystals and high-quality monocrystalline β˗Ga2O3 thin films prepared by mechanical exfoliation. Zhang led the thermal measurements and analysis using an ultrafast laser-based metrology. 

Koester finds the joint nature of the undertaking significant. He says: "This work has been a great collaboration between the ME and ECE departments and shows the power of interdisciplinary research to understand a fundamental property of a material with such incredible promise for practical applications." 

Although gallium oxide can potentially be used in high-power electronics, its relatively low thermal conductivity is a concern as it can lead to device self-heating which can degrade performance. Zhang's work provides fundamental insights into the thermal transport mechanisms that could lead to new ways to design devices to limit self heating, allowing them to take advantage of the benefits that Ga2O3 can provide. 

Commenting on the implications of the research, Koester says, "Gallium oxide is one of the most promising materials to improve efficiency in power conversion systems. This work is an important step in overcoming one of the final barriers to its use in practical applications."

A member of the Micro/Nanoscale Thermal Transport Laboratory group, Yingying Zhang probes the thermal properties of micro/nanostructured materials enabled by time-domain thermoreflectance. More details on the news available at the mechanical engineering department's website.

The poster was co-authored by Koester research group members, Qun Su (ECE alumnus) and postdoctoral associate Sandhya Koirala.