September 17, 2018
Good Morning,
Scientists have created a new silicon chip that has the capability of generating a continuous supply of single photons. Think of the possibilities...
Learn about this and more interesting stories from the scientific community in today's issue.
Until Next Time,
Erin
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*-- Copper nanoparticles, green laser light cost beneficial in circuitry printing --*
Printing electronic circuitry with copper nanoparticle ink and green laser light can be more cost beneficial and efficient, according to a study.
Researchers at Soonchunhyang University in South Korea studied the thin-film printing technique instead of the conventional methods, based on laser power, scanning speed, pre-baking conditions and film thickness effects. Their findings were published this week in the journal AIP Advances.
Nanoparticles in metallic inks have an advantage over bulk metals because of their lower melting points in the circuitry manufacturing.
Originally the researchers, led by Kye-Si Kwon, tested silver nanoparticle ink but found it is costlier. Then, they studied studied copper, which is derived from copper oxide.
Although copper's melting point of copper is nearly 2,000 degrees Fahrenheit, copper nanoparticles can be brought to their melting point at just 300 to 930 through sintering. Then, they can be merged and bound together.
The nanoparticles are heated by the absorption of light.
"A laser beam can be focused on a very small area, down to the micrometer level," the researchers said.
Heat from the laser converts copper oxide into copper and promotes the conjoining of copper particles through melting.
The researchers decided a green laser -- in the 500- to 800-nanometer wavelength absorption rate range -- would be ideal for their purposes. And because green lasers in this role have not been reported elsewhere, Kwon wanted to see how it worked.
The researchers used commercially available copper oxide nanoparticle ink that was spin-coated onto glass at two speeds to obtain two thicknesses. They prebaked the material to dry out most of the solvent before sintering to reduce the copper oxide film thickness and to prevent air bubble explosions when the solvent suddenly boils during irradiation.
They concluded that the prebaking temperature should be slightly lower than 400 degrees F.
In searching for optimal settings of laser power and scanning speed during sintering, they worked to enhance the conductivity of the copper circuits. The found the best results were produced with laser power from 0.3 to 0.5 watts. To reach the desired conductivity, the laser scanning speed should be at least 10 millimeters per second and less than 100.
The researchers concluded that sintering reduces film thickness by as much as 74 percent.
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* New silicon chip emits quantum light source *
Scientists have developed a new silicon chip capable of generating a continuous supply of single photons, a flawless quantum light source.
"Pretty much all of the light we encounter in our everyday lives is packed with photons," Elizabeth Goldschmidt, a research scientist at the Joint Quantum Institute, said in a news release. "But unlike a light bulb, there are some sources that actually emit light, one photon at time, and this can only be described by quantum physics."
Today's communication technologies are mostly powered by non-quantum light, but many believe quantum light will power the next generation of communication and computer technology.
As such, scientists continue to look for ways to reliably produce quantum light, with the aim of isolating and manipulating its quantum properties.
To develop a consistent source of quantum light, Goldschmidt and her research partners turned to silicon. When passed through a layer of silicon, infrared laser light is converted into two different colored photons.
For the new chip, researchers used an array of tiny silicon loops. When infrared light passes through the chip, it races around each loop several thousand times before jumping to the next loop. The design effectively prolongs the light's journey through the silicon, allowing the tiny chip to produce lots of photon pairs.
Scientists have deployed similar photon-producing technologies. Often, minuscule defects in silicon materials cause the color of the emitted photons to vary from chip to chip, device to device. Consistency can even be a problem within a single chip's light-converting material.
Goldschmidt and her colleagues addressed this problem by isolating the silicon loops along the edge of the chip. The design tweak minimized the impact of material defects, enabling the production of identical pairs of single photons.
"We initially thought that we would need to be more careful with the design, and that the photons would be more sensitive to our chip's fabrication process," said Sunil Mittal, a postdoctoral researcher at JQI. "But, astonishingly, photons generated in these shielded edge channels are always nearly identical, regardless of how bad the chips are."
The researchers described their breakthrough technology in the journal Nature this week.
In addition to producing pristine single photons. The technology also works at room temperature. The novel chip could inspire a new generation of quantum devices.
"Physicists have only recently realized that shielded pathways fundamentally alter the way that photons interact with matter," said Mittal. "This could have implications for a variety of fields where light-matter interactions play a role, including quantum information science and optoelectronic technology."
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