Nav: Home

Novel advancements in radiation tolerance of HEMTs

July 12, 2016

When it comes to putting technology in space, size and mass are prime considerations. High-power gallium nitride-based high electron mobility transistors (HEMTs) are appealing in this regard because they have the potential to replace bulkier, less efficient transistors, and are also more tolerant of the harsh radiation environment of space. Compared to similar aluminum gallium arsenide/gallium arsenide HEMTs, the gallium nitride-based HEMTs are ten times more tolerant of radiation-induced displacement damage.

Until recently, scientists could only guess why this phenomena occurred: Was the gallium nitride material system itself so inherently disordered that adding more defects had scant effect? Or did the strong binding of gallium and nitrogen atoms to their lattice sites render the atoms more difficult to displace?

The answer, according to scientists at the Naval Research Laboratory, is none of the above.

Examining radiation response

In a recent open access article published in the ECS Journal of Solid State Science and Technology entitled, "On the Radiation Tolerance of AlGaN/GaN HEMTs," the team of researchers from NRL state that by studying the effect of proton irradiation on gallium nitride-based HEMTs with a wide range of initial threading dislocation defectiveness, they found that the pre-irradiation material quality had no effect on radiation response.

Additionally, the team discovered that the order-of-magnitude difference in radiation tolerance between gallium arsenide- and gallium nitride-based HEMTs is much too large to be explained by differences in binding energy. Instead, they noticed that radiation-induced disorder causes the carrier mobility to decrease and the scattering rate to increase as expected, but the carrier concentration remains significantly less affected than it should be.

Applications in space exploration

Because of their relative radiation hardness, gallium arsenide- and gallium nitride-based HEMTs are desirable for space application. Take, for example, the Juno Spacecraft.

On July 4, the Juno Spacecraft successfully entered orbit around Jupiter - a planet scientists still know very little about, which generates extreme levels of radiation. Without the proper technology, the radiation levels of Jupiter could destroy the sensitive electronics in the satellite upon approaching the planet. Better understanding of why gallium arsenide- and gallium nitride-based HEMTs are more tolerant of radiation could ultimately accelerate innovative and bolster projects where radiation levels prove to be barriers.

Novel advancements in HEMTs

The paper was designated ECS Editors' Choice due to its significance and expected impact on the solid state science and technology community.

"Editors' Choice articles are elite publications because they are deemed by reviewers and journal editors to demonstrate a transformative advance, discovery, interpretation, or direction in a field," says Dennis Hess, Editor of the ECS Journal of Solid State Science and Technology. "They represent very high quality science and engineering and hold the promise of altering current technology practices."

Unexpected answers

The explanation for this novel discovery turns out to be rather elegant.

In gallium nitride-based HEMTs, a piezoelectric field forms at the aluminum gallium nitride/gallium nitride interface due to lattice strain. The field gives rise to two-dimensional electron gas by which carriers travel across the transistor from source to drain. It also provides an electrically attractive environment that causes carriers that are scattered out of the two-dimensional electron gas by radiation-induced defects to be reinjected. In this way, the scattering rate can increase and the mobility can decrease without greatly affecting the two-dimensional electron gas carrier density.

In other words, it is the internal structure itself that renders aluminum gallium nitride/gallium nitride HEMTs rad-hard.

"Gallium nitride is such a complicated system - not like gallium arsenide at all," says Bradley Weaver, co-author of the study. "We struggled for four years to figure out why it's so rad-hard, expecting a complicated solution. But the answer turned out to be really simple. Science does that sometimes."

The Electrochemical Society

Related Radiation Articles:

What membrane can do in dealing with radiation
USTC recently found that polymethylmethacrylate (PMMA) and polyvinyl chloride (PVC) can release acidic substance under γ radiation, whose amount is proportional to the radiation intensity.
First measurements of radiation levels on the moon
In the current issue (25 September) of the prestigious journal Science Advances, Chinese and German scientists report for the first time on time-resolved measurements of the radiation on the moon.
New biomaterial could shield against harmful radiation
Northwestern University researchers have synthesized a new form of melanin enriched with selenium.
A new way to monitor cancer radiation therapy doses
More than half of all cancer patients undergo radiation therapy and the dose is critical.
Nimotuzumab-cisplatin-radiation versus cisplatin-radiation in HPV negative oropharyngeal cancer
Oncotarget Volume 11, Issue 4: In this study, locally advanced head and neck cancer patients undergoing definitive chemoradiation were randomly allocated to weekly cisplatin - radiation {CRT arm} or nimotuzumab -weekly cisplatin -radiation {NCRT arm}.
Breaking up amino acids with radiation
A new experimental and theoretical study published in EPJ D has shown how the ions formed when electrons collide with one amino acid, glutamine, differ according to the energy of the colliding electrons.
Radiation breaks connections in the brain
One of the potentially life-altering side effects that patients experience after cranial radiotherapy for brain cancer is cognitive impairment.
Fragmenting ions and radiation sensitizers
The anti-cancer drug 5-fluorouracil (5FU) acts as a radiosensitizer: it is rapidly taken up into the DNA of cancer cells, making the cells more sensitive to radiotherapy.
'Seeing the light' behind radiation therapy
Delivering just the right dose of radiation for cancer patients is a delicate balance in their treatment regime.
Radiation contamination at a crematorium
Radioactive compounds known as radiopharmaceuticals are used in nuclear medicine procedures to diagnose and treat disease.
More Radiation News and Radiation Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at     You can read The Transition Integrity Project's report here.