Diamond continues to shine: new properties discovered in diamond semiconductors

CLEVELAND and CHAMPAIGN-URBANA, ILL.—Diamond, often celebrated for its unmatched hardness and transparency, has emerged as an exceptional material for high-power electronics and next-generation quantum optics. Diamond can be engineered to be as electrically conductive as a metal, by introducing impurities such as the element boron.

Researchers from Case Western Reserve University and the University of Illinois Urbana-Champaign have now discovered another interesting property in diamonds with added boron, known as boron-doped diamonds. Their findings could pave the way for new types of biomedical and quantum optical devices—faster, more efficient, and capable of processing information in ways that classical technologies cannot. Their results are published today in Nature Communications.

The researchers found that boron-doped diamonds exhibit plasmons—waves of electrons that move when light hits them—allowing electric fields to be controlled and enhanced on a nanometer scale. This is important for advanced biosensors, nanoscale optical devices, and for improving solar cells and quantum devices. Previously, boron-doped diamonds were known to conduct electricity and become superconductors, but not to have plasmonic properties. Unlike metals or even other doped semiconductors, boron-doped diamonds remain optically clear.

“Diamond continues to shine” said Giuseppe Strangi, professor of physics at Case Western Reserve, “both literally and as a beacon for scientific and technological innovation. As we step further into the era of quantum computing and communication, discoveries like this bring us closer to harnessing the full potential of materials at their most fundamental level.”

“Understanding how doping affects the optical response of semiconductors like diamond changes our understanding of these materials,” said Mohan Sankaran, professor of nuclear, plasma and radiological engineering at Illinois Grainger College of Engineering.

Plasmonic materials, which affect light at the nanoscale, have captivated humans for centuries, even before their scientific principles were understood. The vibrant colors in medieval stained-glass windows result from metal nanoparticles embedded in the glass. When light passes through, these particles generate plasmons that produce specific colors. Gold nanoparticles appear ruby red, while silver nanoparticles display a vibrant yellow. This ancient art highlights the interaction between light and matter, inspiring modern advancements in nanotechnology and optics.

Diamonds, composed of transparent crystals of the element carbon, can be synthesized with small amounts of boron, adjacent to carbon on the periodic table. Boron contains one less electron than carbon, allowing it to accept electrons. Boron essentially opens up a periodic electronic “hole” in the material that has the effect of increasing the ability of the material to conduct current. The boron-doped diamond lattice remains transparent, with a blue hue. (The famous Hope Diamond is blue because it contains small amounts of boron).

Because of its other unique properties—it’s also chemically inert and biologically compatible—boron-doped diamond could potentially be used in contexts that other materials could not, such as for medical imaging or high-sensitivity biochips or molecular sensors..

Diamonds synthesized at low pressure were pioneered at Case Western Reserve (then Case Institute of Technology) in 1968 by faculty member John Angus, who died in 2023. Angus was also the first to report on the electrical conductivity of diamond doped with boron.

Strangi and Sankaran collaborated with Souvik Bhattacharya, lead author, a graduate student at Illinois; Jonathan Boyd, Case Western Reserve; Sven Reichardt and Ludger Wirtz, University of Luxembourg; Vallentin Allard, Aude Lereu and Amir Hossein Talebi, Marseilles University; and Nicolo Maccaferri, Umeå University, Sweden.

The research was supported by the National Science Foundation.

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At Case Western Reserve, one of the nation's leading research universities, we're driven to seek knowledge and find solutions to some of the world's most pressing problems. Nearly 6,200 undergraduate and 6,100 graduate students from across 96 countries study in our more than 250 degree programs across arts, dental medicine, engineering, law, management, medicine, nursing, science and social work. Our location in Cleveland, Ohio—a hub of cultural, business and healthcare activity—gives students unparalleled access to engaging academic, research, clinical, entrepreneurial and volunteer opportunities and prepares them to join our network of 125,000+ alumni making an impact worldwide. Visit case.edu to learn more.

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The Grainger College of Engineering at the University of Illinois Urbana-Champaign upholds its reputation as a top-ranked engineering college by delivering engineering education that isn’t beholden to commonality. Innovation here comes from the pursuit of a more diverse student body, programs that emphasize collaboration, methodology that commits to hands-on learning, and research that boldly answers difficult questions. Our land-grant mission grounds us, and our accomplishments include advancements in the MRI, LED, ILIAC, Mosaic, YouTube, flexible electronics, electric machinery, miniature batteries, imaging the black hole and much more. With fortitude, determination, and dogged commitment to a brighter future, we don’t just make a difference; we create the difference. And that difference will construct a better future for everyone. Visit https://www.grainger.illinois.edu/ for more information.

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