Research
discoveries that have translated to applications
We delight in every tiny
scientific nugget we uncover in our daily research. Some of these unexpectedly
lead to practical applications. Here is
a list of some that we were fortunate to see go from scratching our heads to
understand mysterious data collected in the lab, to projects and products in
the industry.
1. Discovery of distributed
polarization doping for mobile electrons (n-type doping) in wide bandgap
semiconductors in 2002 (link),
and its use for the first PolFET in 2002 (chapter 5
of my PhD thesis,
and patent). See how our discovery has enabled transistors
pursued by industry here.
2. Discovery of distributed
polarization doping for mobile holes (p-type doping) in wide bandgap
semiconductors in 2009 (link)
and its use in UV LEDs (patent). The p-type doping of GaN with the acceptor Mg
that enabled blue LEDs and lasers in 1990s and 2000s (see the 2014 Physics
Nobel Lectures 1, 2, 3)
was insufficient to realize UV lasers with wider bandgap AlGaN
and AlN. See how our discovery of distributed polarization doping was used by industry
to realize the first ever electrically injected deep-UV semiconductor laser in
2019 (link)
and its CW operation in 2022 (link).
3. Discovery of ultrahigh density
2D hole gases at undoped wide bandgap semiconductor heterojunctions due to
polarization discontinuity in 2019 (link).
Even though p-type doping of GaN with the acceptor Mg had enabled blue LEDs and
lasers in 1990s and 2000s (see the 2014 Physics Nobel Lectures 1, 2, 3),
the hole density remained insufficient for high-performance p-channel
transistors. Our 2019 discovery of the
ultrahigh density 2D hole gases (see patent)
enabled us to demonstrate the first ever RF p-channel GaN transistors in 2020 (link).
Also see our p-FET device patent.
Research
inventions with high application potential in the near-future
While some of our group’s
research have seen applications in industry, theory, modeling, and a bit of
leap of faith allow us to conceive devices outside of available materials and
processing technology of the time. Here
are a few examples. Over time, ingenuity
of the research community has brought some of them to fruition.
1. GNRTFETs: 2008 proposal,
and a realization. Takes advantage of the unique property of 2D
materials for energy-efficient electronic switches.
2. TMDFETs: 2012 realization
in collaboration with Samsung of the first 2D material channel FETs to show
current saturation and near ideal switching.
3. SymFETs: 2012 theory,
proposal,
and a realization. Uses interlayer tunneling between 2D
materials. Related to BISFETs, and Moire lattices in twisted 2D layers.
4. ThinTFETs: 2014 proposal,
and a realization. Uses interlayer tunneling between 2D
materials for energy-efficient electronic switches.
5. PiezoFETs: 2014 proposal
using active gate barriers in polar semiconductors.
6. GaN TFETs: 2016 proposal,
patent,
and a 2020 realization. Uses high internal fields in polar
semiconductors for energy-efficient electronic switches.
7. LEFETs: 2018 patent, and a realization. LEDs and FETs in the same device for photonic
communications and LiFi.
8. GOFETs: 2018 patent
and a realization. Gallium oxide power transistors for energy
efficient electronics.
9. UV LEDs/Lasers: 2018 patent
and realizations using quantum structures and distributed polarization doping
with GaN quantum dots in 2014 (link),
and ultrathin GaN quantum wells in 2017 (link,
link).
10. UV LEDs/Lasers: 2018 patent,
and realizations using distributed polarization doping with tunnel junctions in
2017 (link),
and distributed polarization p-doping in 2017 (link).
11. SOTFETs: 2020 collaborative proposal
of the Spin-orbit torque FET as a logic/memory hybrid device for associative
memories (link),
and materials to realize them (link).
12. FerroHEMTs: 2022 first realization.
Polar semiconductor based ferroelectric transistors for RF/mm-wave electronic
communications, digital electronics for logic, and non-volatility for memory -
all in one device!
Stay
tuned for more!