"Thermal Engineering of Wide Bandgap Semiconductors"


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Monday, October 1, 2018 -
11:00am to 12:00pm
Brauer Hall, Room 12
Prof. Samuel Graham, Woodruff School of Mechanical Engineering, Georgia Institute of Technology

Wide bandgap electronics made from Gallium Nitride (GaN) and Gallium Oxide (Ga2O3) are currently under development due to their potential to create some of the most advanced RF, power electronic, and optoelectronic devices in the world. However, these devices can operate at high power densities and electric fields which makes their thermal control and device reliability a challenge.  The vast majority of GaN electronics are grown heteroepitaxially onto non-native substrates which introduces defects into devices and inherently requires several interfaces that can impede heat dissipation from the devices.  Thus, it is the control of the material during the growth phase that allows engineers to impact their electrothermal behavior, leading to advanced high-power density devices that are expected in the future. For Ga2O3, homoepitaxy is possible, but the thermal properties of gallium oxide are low and present additional thermal challenges.  Considering that heat fluxes from these devices can greatly exceed 1 kW/cm2, advanced thermal control solutions integrated within the device architecture and accurate thermal metrology to verify the reduction in device junction temperature are needed to improve the thermal performance and reliability of GaN electronics.

In this talk we will discuss advancements in thermal characterization techniques that have allowed new insights into GaN and Ga2O3 materials and devices, with a specific focus on the role of device architecture and processing on their thermal performance.  This will include high speed transient thermoreflectance and gate resistance thermometry methods developed in our group.  We will discuss in some detail the role of interfaces on the thermal boundary resistance and the fundamental challenges that must be addressed to lead to the tailoring of this thermal resistance in the devices. We will then discuss advancements in RF and power electronic devices including those made on bulk GaN and Ga2O3 substrates and the thermal challenges and opportunities that exist for recent bulk GaN technology. 


Samuel Graham is the Eugene C. Gwaltney, Jr. Professor and Chair of the Woodruff School of Mechanical Engineering at the Georgia Institute of Technology.  He leads the Electronics Manufacturing and Reliability Laboratory which is focused on the electrical and thermal characterization, packaging, and reliability of wide bandgap semiconductors, solar cells, and flexible electronics.  He also holds a courtesy appointment in the School of Materials Science and Engineering at Georgia Tech, a joint appointment with Oak Ridge National Laboratory, and is a Visiting Professor at Nagoya University in Nagoya, Japan. He is a Fellow of ASME, a member of the Engineering Sciences Research Foundation Advisory Board of Sandia National Laboratories and Air Force Scientific Advisory Board.

 Host: Damena Agonafer

Faculty, students, and the general public are invited.





Hosted by: Damena Agonafer

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