Reliability Study of GaN-Based Hall Sensors
Student: Alexis Krone
Degree: M.S., May 2021
Major Professor: Dr. David Huitink
Research Area(s):
Microelectronics
Physical & Chemical Sensors
Background/Relevance
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Current magnetic field sensors use silicon-based substrates but break down under high temperatures and voltages.
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As industry shifts to higher power electronics in uses such as cars, stable wide band gap semiconductor-based devices are needed.
Innovation
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Use GaN-based Hall Effect Sensors to monitor magnetic fields in motors due to substrate stability
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Model failure modes and corollate them to new alloy generations at higher temperatures.
Approach
- Measure the initial material electrical properties of Hall sensors fabricated at UARK and Stanford.
- Subject samples to accelerated thermal aging with different temperature and time scales
- Repeat electrical and material measurements and compare with initial.
- Use electrical and material measurements to generate a representation of the reliability and ideal operating temperatures and lifetimes.
Key Results
- Stanford AlGaN/GaN devices showed a steady increase in resistance during 450 C tests and leveled around 50 hours into accelerated aging tests
- Stanford InAlN/GaN devices appeared stable through 48 hours at 450 C
- UARK GaN appeared to have interdiffusion events
Conclusions
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Smaller time scales at 200 C have overall stable device electrical properties.
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Temperatures above 450 C result in physical changes which may impact contact reliability.
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Contacts are the most likely part of the devices to fail.
Future Work
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Subject newly designed devices to higher temperature environments and longer durations.
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Measure interdiffusion events after failure.
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Investigate effects of thermally aging samples in inert environments.
