MSE Seminar: Dr. Georges Pavilidis, University of Connecticut
Wednesday, September 28, 2022
3117 Computer Science Instructional Center (CSI) Bldg # 406 and Via Zoom
301 405 5240
Enhancing thermal transport across interfaces: Transitioning from the microscale to nanoscale
Wide bandgap semiconductors have shown great potential for RF devices and power electronics. Their superior material properties have enabled the fabrication of high power and high frequency devices. Their performance, however, has been limited by significant localized Joule heating. The quantification of operational parameters such as the gate temperature is thus necessary to accurately assess the device's quality and lifetime. The first part of the talk will present novel methods for in-situ transient temperature measurements of various devices with different geometries and advanced thermal management solutions. This includes developing a near bandgap thermoreflectance imaging technique and performing the first ever cross-sectional thermal image of a GaN transistor. While micrometer resolution thermal characterization techniques are advantageous, the feature size of electronics is continually reducing. Characterization tools that can capture transport phenomena on the nanoscale are thus necessary. The second part will cover Atomic Force Microscopy (AFM) based techniques used to obtain thermal properties with nanometer resolution. This includes scanning thermal microscopy (SThM) of neuromorphic devices for emerging bio-inspired circuits; GaN superlattice FETs for high frequency applications; and Gallium Oxide based power transistors. Additionally, a coupled AFM-IR technique is introduced using novel optomechanical probes for interfacial thermal conductance mapping. Compared to traditional AFM, these probes demonstrate a 50x improvement in the signal to noise ratio and increase the time resolution to 10 ns.
Dr. Georges Pavlidis joined the Department of Mechanical Engineering at the University of Connecticut as an Assistant Professor in 2022. Prior to that, he was an NRC Postdoctoral Researcher in the Nanoscale Spectroscopy Group. He earned his M.Eng in Mechanical Engineering from Imperial College London in 2013 and his Ph.D. degree in Mechanical Engineering from the Georgia Institute of Technology in 2018. Dr. Pavlidis specializes in the thermal characterization of WBG semiconductors for RF and power electronics. He has developed electrical/optical methods, with high spatial and temporal resolution, to assess the performance and reliability of III-nitrides devices. His recent publications investigate improving hBN polariton lifetimes and developing high throughput techniques for interfacial thermal conductance mapping.