Kexin Li
Arizona State University Campus Immersion, AZ·Engineering
Quantum computers, spacecraft, superconducting equipment and high-performance computers all need electronics that work reliably at extremely cold (cryogenic) temperatures. Transistors made from gallium nitride (GaN), already used for high-power and high-frequency electronics, are promising here.
- Fields
Engineering
Physics
Materials Science
- Topics
gallium nitride
GaN
high-electron-mobility transistor
- Grants
- 1 known grant, through Sep 2029
What they work on
- Develop a cryogenic compact model for gallium nitride high-electron-mobility transistors (HEMTs) by extending an existing quasi-ballistic model. Capture how electron transport, self-heating and charge trapping change as temperature drops.
- Adapt the cryogenic compact model to fin-shaped transistors and nanowire devices and use it in circuit simulations, linking device physics to whole-circuit performance from room to cryogenic temperatures.
- Couple a full-band Monte Carlo solver, which statistically tracks electron motion and scattering, with heat-flow and quantum-mechanical calculations. Calibrate the results against current-voltage and high-frequency measurements.
- Build fast physics-informed machine-learning substitutes for costly simulations and use Bayesian optimization to select GaN device designs that balance circuit performance, process variation, reliability and cost.
More about the research
Their electron channels stay robust in the cold, and electrons can move more easily as temperature drops. But engineers lack fast, reliable ways to predict how cooling changes electron motion, heat buildup and sensitivity to manufacturing variation. Cold measurements are also costly and difficult.
Why it matters
Reliable cold-temperature electronics are needed for quantum computing, space missions, superconducting systems and high-performance computing. Fast, predictive models for GaN transistors could help chip designers pick device structures and materials that perform well in extreme cold. This could reduce the need for repeated expensive low-temperature experiments and help limit fabrication cost and reliability risk.
Known grants
From NIH and NSF research grants. Labs often have other funding we can't see.
Closest labs
Yuping Zeng
University of Delaware, DE·Engineering·Early-career
Find the material, surface and interface causes that make GaN-on-Si high electron mobility transistors perform worse than GaN-on-SiC devices, by linking fabrication process steps to measured device performance.
Shubhra Pasayat
University of Wisconsin-Madison, WI·Engineering·Early-career
Develop porous semiconductor substrates that are mechanically flexible and reflective, to relieve strain in III-nitride ultraviolet LED layers and redefine their critical thickness limits.
Jivtesh Garg
University of Oklahoma, OK·Engineering
Test whether evanescent electric fields across 2–4 Å interfacial gaps help acoustic phonons, the lattice vibrations that carry heat, cross GaN–diamond interfaces, using atomistic Green's function calculations.
The school
Arizona State University Campus Immersion: 36 labs on PI Pages, $1.0B a year on research, 625 research doctorates a year.
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