2024 Investiture Information

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Developing and Deploying Gallium Nitride Magnetometers for Harsh Environments



3:30pm - 4:30pm ET


Meeting ID: 982 6654 1765
Passcode: 747907

Gallium nitride (GaN) and silicon carbide (SiC) are two key wide bandgap (WBG) materials rapidly replacing silicon in high-speed communications and power systems. These materials also can operate in extreme temperature ranges, from cryogenic temperatures to 1000°C. GaN, in particular, has the ability to support a confined charge layer, commonly referred to as a two-dimensional electron gas (2DEG). This phenomenon is key to high-frequency, high-power RF transmission in 5G networks, and is also a great sensing layer for various environmental stimuli (i.e. Thermal, Magnetic, Strain). Additionally, various GaN sensors and transistors can be fabricated with the same fabrication process, which can lead to monolithically integrated systems on a single chip. GaN magnetometers are an important component in the future of WBG microsystems with their broad applications from power electronics monitoring to navigation in extreme environments.

In this talk, I will describe an AlGaN/GaN 2DEG Hall-effect plate with ~100 ppm/K drift, 0.5 micro-Tesla offset, and 200 Hz corner frequency. In addition, the GaN 2DEG Hall-effect plates have operated in an extended temperature range from 50 K to 600°C. These metrics beat out state-of-the-art silicon Hall-effect sensors. Through this work, I have created a record-low offset in GaN 2DEG Hall devices, presented a framework for studying noise in GaN Hall sensors, and initiated steps towards integration of Hall-effect devices in microsystems for Low earth orbit and current sensing in transformers. I will then present new concepts for novel GaN sensors with a micromachined substrate and highlight additional work with fabrication of SiC for MEMS and Power management. These contributions will enable a future monolithically integrated GaN platform for power electronics and extreme environments. I will also include future interests using ultra-wide bandgap materials for sensing, opto-electronics and future extreme environment deployment targets that can be enabled by this technology.

About the Speaker(s)

Karen Dowling
Postdoctoral Researcher, Lawrence Livermore National Laboratory

Karen Dowling is a postdoctoral researcher at Lawrence Livermore National Laboratory. Her research interests include the use of wideband gap materials for the development of sensors for extreme environments, in particular magnetic field sensors for power electronic systems and navigation for exploration. Currently she focuses on opto-electronics for power and RF devices.

She received her BS degree in electrical engineering from the California Institute of Technology, Pasadena CA in 2013 and MS degree in electrical engineering from Stanford University, CA in 2015. She received her PhD in electrical engineering at Stanford University in 2019. Dr. Dowling was a National Science Foundation Graduate Research Fellow and the student president of the NSF engineering research center for power optimization of electro-thermal systems. In 2018, she received a fellowship to work with Infineon Technologies in Munich, Germany in both the Innovative Sensors Group and the Silicon Carbide Industrial Power Group.


For more information, contact Ashley Parker at ashley.l.parker@dartmouth.edu.