A 'recipe book' that creates color centers in silicon carbide crystals

October 1, 2018, American Institute of Physics
Green SiC substrate at the bottom with the graphene layer on top irradiated by protons, generating a luminescent defect in the SiC crystal. Credit: Maximilian Rühl

Silicon carbide (SiC), a material known for its toughness with applications from abrasives to car brakes, to high-temperature power electronics, has enjoyed renewed interest for its potential in quantum technology. Its ability to house optically excitable defects, called color centers, has made it a strong candidate material to become the building block of quantum computing.

Now, a group of researchers has created a list of "recipes" physicists can use to create specific types of defects with desired optical properties in SiC. In one of the first attempts to systematically explore color centers, the group used irradiation techniques to create the color centers in . They adjusted proton dose and temperature to find the right conditions that reliably produce the desired type of color center. The team reports their findings in Applied Physics Letters.

Atomic defects in the lattice of SiC crystals create color centers that can emit photons with unique spectral signatures. While some materials considered for require cryogenically low temperatures, color centers in SiC can emit at room temperature. As the push to create increasingly smaller devices continues into atom-scale sensors and single-photon emitters, the ability to take advantage of existing SiC integrated circuit technology makes the material a standout candidate.

To create the defects, Michael Krieger and his colleagues bombarded SiC samples with protons. The team then let the SiC go through a heating phase called annealing. "We're doing a lot of damage to these crystals," Krieger said. "However, during annealing, the crystal structure recovers, but defects are also formed—some of them are the desired centers."

To ensure that their recipes are compatible with usual semiconductor technology, the group opted to use proton irradiation. Moreover, this approach doesn't require electron accelerators or nuclear reactors like other techniques used to create .

The data from using different doses and annealing temperatures showed that producing defects in SiC follows a pattern. Initially protons generate predominantly silicon vacancies in the crystal, then those vacancies sequentially transform into other complexes.

Studying the defects' low-temperature photoluminescence spectra led the team to discover three previously unreported signatures. The three temperature-stable (TS) lines were shown to correlate with proton dose and annealing temperature.

Krieger said these TS lines have exciting properties and further research is already going on as the group hopes to utilize and control those defects for use in SiC-based quantum technology devices.

Explore further: Defects promise quantum communication through standard optical fiber

More information: M. Rühl et al, Controlled generation of intrinsic near-infrared color centers in 4H-SiC via proton irradiation and annealing, Applied Physics Letters (2018). DOI: 10.1063/1.5045859

Related Stories

New materials bring quantum computing closer to reality

May 9, 2017

For 60 years computers have become smaller, faster and cheaper. But engineers are approaching the limits of how small they can make silicon transistors and how quickly they can push electricity through devices to create digital ...

Diamonds' flaws hold promise for new technologies

January 19, 2018

Despite their charm and allure, diamonds are rarely perfect. They have tiny defects that, to assistant professor Nathalie de Leon, make them ever so appealing. These atom-sized mistakes have enormous potential in technologies ...

Physicists reveal material for high-speed quantum internet

March 21, 2018

Researchers from the Moscow Institute of Physics and Technology have rediscovered a material that could be the basis for ultra-high-speed quantum internet. Their paper published in npj Quantum Information shows how to increase ...

Recommended for you

CMS gets first result using largest-ever LHC data sample

February 15, 2019

Just under three months after the final proton–proton collisions from the Large Hadron Collider (LHC)'s second run (Run 2), the CMS collaboration has submitted its first paper based on the full LHC dataset collected in ...

Gravitational waves will settle cosmic conundrum

February 14, 2019

Measurements of gravitational waves from approximately 50 binary neutron stars over the next decade will definitively resolve an intense debate about how quickly our universe is expanding, according to findings from an international ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.