Development of Micro-Hall Devices for Current Sensing

Student: Thomas White

Degree: Ph.D., May 2020

Major Professor: Dr. Alan Mantooth and Dr. Greg Salamo

Research Area(s):

Microelectronics

Physical & Chemical Sensors

Improve power inverter efficiency by using passive simultaneous current and temperature sensing devices.

Develop a method for simultaneous current and temperature sensing without amplification.
Increase sensor’s sensitivity to current and temperature while maintaining ability to operate in harsh environments.

Explore wide bandgap material structures in order to achieve a current and temperature sensor capable of operating at temperatures grater than 200 °C.
Research and install growth parameters to fabricate GaN HEMT structures by MBE.
Fabricate and characterize micro-Hall current and temperature sensors.
Design new die layouts as well as new packaging solutions.

Improved B-Field sensitivity by 3x (see graph) when compared to highest published sensitivity for GaN-based sensors.
Achieved a linear response to magnetic field in a wide temperature range.
Measured a current sensitivity of 10 mV/A with no amplification circuitry.
Simultaneously measured current and temperature with a single Hall cell
Demonstrated stability in both current and temperature measurements across the temperature range of -50 – 250 °C.

The wide bandgap AlGaN/GaN structure was stable across the temperature range of -50 – 250 °C. No ionization impact phenomena was observed in the AlGaN/GaN devices.
A Schottky biased contact improved the B-field sensitivity of the GaN-based devices, which measured 5 A of current passing through a trace. The 10 mV/A sensitivity and 5 A minimum current detection limit was measured at a trace-sensor distance of 3 mm.
The sensor’s magnetic and temperature sensitivities was found to be as high as 240 V/A/T (at RT) and 1.7 mV/°C respectively.