How NREL’s Brooks Tellekamp Explores the Next Generation of Materials for More Efficient LEDs and Power Electronics | News Ali Guerra | usagoldmines.com

Share

Brooks Tellekamp discovered his strategy to science by way of his highschool’s computing infrastructure.
He helped the college’s info expertise professional, a retired Honeywell engineer
who had labored on NASA contracts, to deal with computing infrastructure wants.

These early experiences set Tellekamp on a transparent path—he focused engineering faculty
in consequence.

“I discovered myself in a cooperative work program at a zinc oxide semiconductor bulk progress
startup,” stated Tellekamp, a supplies science researcher on the Nationwide Renewable
Vitality Laboratory (NREL). “An worker on the firm beneficial that I take lessons
with Alan Doolittle, who would go on to recommend I pursue a graduate diploma in his
laboratory. Alongside the way in which, I by no means thought-about analysis as a chance, however getting
the chance to work within the Doolittle lab actually modified that.”

That unlikely path introduced Tellekamp to NREL, and now he has been acknowledged by the
Journal of Physics D: Utilized Physics as an emerging leader in a special issue of the journal.

Synthesizing Key Supplies

Tellekamp clearly recollects an early breakthrough in his profession: In graduate faculty
on the Georgia Institute of Expertise, after years attempting to synthesize a fabric
whose synthesis secrets and techniques had been misplaced, he efficiently synthesized lithium niobite
(LiNbO₂). The fabric is a memristor—a tool used to imitate synapses for neuromorphic computing.
This method to computing mimics the human mind’s functioning.

Tellekamp then arrived at NREL as a postdoc to work on analysis in an space that was
new to him: ternary nitrides. Tellekamp has carried his previous work on neuromorphic
computing into his work at NREL, reviewing chalcogenide supplies for this utility
and demonstrating the memristive properties of another oxide material, NdNiO₃. From there, he has targeted on next-generation oxide and nitride semiconductors for
energy electronics purposes.

In one other breakthrough, Tellekamp and staff have been in a position to synthesize a gallium oxide (Ga₂O₃)-indium (III) oxide alloy, one other semiconducting materials with energy electronics purposes.

“We have been having bother getting the indium to enter the Ga₂O₃ crystal,” Tellekamp stated. “We usually use a technique of sprucing away a few of the
Ga₂O₃ crystal with gallium at excessive temperatures to scrub the floor earlier than progress, and
after one other unsuccessful progress (we are able to monitor in actual time with electron diffraction), I requested
Stephen Schaefer, a postdoc engaged on the undertaking, to attempt to etch away the movie utilizing
gallium and simply begin over once more. This led to the event of a cyclical progress/etch
technique that we used to quickly span the expansion house, which elevated our throughput
by about six instances and our substrate utilization by about 46 instances. That was a enjoyable
‘aha’ second.”

Tellekamp’s work on ternary nitride semiconductors has introduced him and colleagues
good consideration. Ternary nitrides have the potential to offer extra energy-efficient
light-emitting diodes (LEDs). His postdoctoral work targeted on ternary nitrides—synthesizing them at high quality, growing them on different substrates to know their optical properties, and demonstrating high-quality interfaces between ZnGeN₂ and Gallium Nitride (GaN). All of this has led to the demonstration of growth of GaN and ZnGeN2 superlattices by way of molecular beam epitaxy—an essential step towards extra environment friendly LEDs. This
work was featured as a part of the rising chief recognition. ZnGeN₂ poses an alternative choice to GaN, a compound semiconductor in LEDs that are very environment friendly
at making blue gentle however not so environment friendly for inexperienced and amber gentle wanted for heat
white indoor lighting. ZnGeN₂ has an identical construction to GaN—making it extremely appropriate—and it might doubtlessly
allow extra energy-efficient inexperienced and amber LEDs with out the necessity for uncommon earth
parts at the moment used to translate blue gentle into white gentle.

Semiconductors: The Subsequent Technology

The following technology of ultrawide-bandgap semiconductors at the moment occupies Tellekamp’s
time at NREL. He’s engaged on semiconductors with extra purposes throughout energy
electronics and excessive setting electronics. Ultrawide-bandgap supplies have
historically been insulators—generally not nice ones—however Tellekamp famous that the
skill to manage conductivity in these compounds has turned out to be essential
for an electrified economic system. “Electrification solely is sensible in the event you can handle all
the ability necessities in an environment friendly and cost-effective manner, and these ultrawide-bandgap
supplies allow this effectivity,” he stated.

“A technique we’re pursuing this proper now’s by way of the invention and design of recent
ultrawide-bandgap supplies, which a few of my collaborators theoretically predicted and I’m now attempting to synthesize. One other manner is thru the event of producing
strategies for vertical (quite than lateral) units utilizing a well-studied materials,
(Al,Ga)N (AlGaN), which is an alloy of gallium nitride (your whole LEDs are made
of this) and aluminum nitride. I had a undertaking funded internally a couple of years in the past to
determine how to do that, and we got here up with a strategy to deposit tantalum carbide thin films in a cost-effective way but make them high enough
quality to grow AlGaN on top of them.” 

Tellekamp and fellow researchers are taking this analysis right into a recently funded Energy Frontier Research Center program led by NREL’s Nancy Haegel:
A Center for Power Electronics Materials and Manufacturing Exploration (APEX). Tellekamp will colead the work on this matter.

Tellekamp aspires to proceed making progress on vertical AlGaN digital units.

“I hope we are able to get to a degree the place the units may be lifted off from our designed
substrates, enabling each higher thermal administration and substrate reuse,” Tellekamp
stated. “There are such a lot of experiments alongside the way in which to understanding how interfaces
of dissimilar supplies wish to go collectively, after which it’s a must to learn to handle
new forms of defects, however I hope that inside the subsequent 5 years we may have demonstrated
this as a viable expertise to enhance the power effectivity of power-demanding purposes.

“On the oxide (quite than nitride) facet of issues, I believe we’ll see gallium oxide
take some fairly drastic leaps by way of price, efficiency, and adoption. Already,
the tempo has been exhausting—the primary gallium oxide transistor was solely developed
12 years in the past—but I believe within the subsequent 5 years we’ll see gallium oxide units
hitting the market whereas research-level units begin to often exceed 10-kV breakdown
voltages. I hope that our primary science investigations of Ga₂O₃ and the interfaces fashioned with different supplies play a component in that advance.”

Study extra about Brooks Tellekamp’s work and about NREL’s materials science research.