Engineers at the University of California San Diego have fabricated the first semiconductor-free, optically-controlled microelectronic device. Using metamaterials, engineers were able to build a microscale device that shows a 1,000 percent increase in conductivity when activated by low voltage and a low power laser.
The discovery paves the way for microelectronic devices that are faster and capable of handling more power, and could also lead to more efficient solar panels. The work was published Nov. 4 in Nature Communications.
This is the designed semiconductor-free microelectronic device.
Credit: UC San Diego Applied Electromagnetics Group
The capabilities of existing microelectronic devices, such as transistors, are ultimately limited by the properties of their constituent materials, such as their semiconductors, researchers said.
For example, semiconductors can impose limits on a device's conductivity, or electron flow. Semiconductors have what's called a band gap, meaning they require a boost of external energy to get electrons to flow through them. And electron velocity is limited, since electrons are constantly colliding with atoms as they flow through the semiconductor.
A team of researchers in the Applied Electromagnetics Group led by electrical engineering professor Dan Sievenpiper at UC San Diego sought to remove these roadblocks to conductivity by replacing semiconductors with free electrons in space. "And we wanted to do this at the microscale," said Ebrahim Forati, a former postdoctoral researcher in Sievenpiper's lab and first author of the study.
However, liberating electrons from materials is challenging. It either requires applying high voltages (at least 100 Volts), high power lasers or extremely high temperatures (more than 1,000 degrees Fahrenheit), which aren't practical in micro- and nanoscale electronic devices.
To address this challenge, Sievenpiper's team fabricated a microscale device that can release electrons from a material without such extreme requirements. The device consists of an engineered surface, called a metasurface, on top of a silicon wafer, with a layer of silicon dioxide in between. The metasurface consists of an array of gold mushroom-like nanostructures on an array of parallel gold strips.
The gold metasurface is designed such that when a low DC voltage (under 10 Volts) and a low power infrared laser are both applied, the metasurface generates "hot spots"--spots with a high intensity electric field--that provide enough energy to pull electrons out from the metal and liberate them into space.
Tests on the device showed a 1,000 percent change in conductivity. "That means more available electrons for manipulation," Ebrahim said.
"This certainly won't replace all semiconductor devices, but it may be the best approach for certain specialty applications, such as very high frequencies or high power devices," Sievenpiper said.
According to researchers, this particular metasurface was designed as a proof-of-concept. Different metasurfaces will need to be designed and optimized for different types of microelectronic devices.
"Next we need to understand how far these devices can be scaled and the limits of their performance," Sievenpiper said. The team is also exploring other applications for this technology besides electronics, such as photochemistry, photocatalysis, enabling new kinds of photovoltaic devices or environmental applications.
Full paper: "Photoemission-based microelectronic devices." Authors of the study are Ebrahim Forati, Tyler J. Dill, Andrea R. Tao and Dan Sievenpiper.
This work was funded by Defense Advanced Research Projects Agency (grant N00014-13-1-0618) and the Office of Naval Research Defense University Research Instrumentation Program (grant N00014-13-1-0655).
Liezel Labios | EurekAlert!
Meta-surface corrects for chromatic aberrations across all kinds of lenses
21.11.2018 | Harvard John A. Paulson School of Engineering and Applied Sciences
Photovoltaic Systems adapted to their environment - project Infinity successfuly completed
21.11.2018 | CTR Carinthian Tech Research AG
Innsbruck quantum physicists have constructed a diode for magnetic fields and then tested it in the laboratory. The device, developed by the research groups led by the theorist Oriol Romero-Isart and the experimental physicist Gerhard Kirchmair, could open up a number of new applications.
Electric diodes are essential electronic components that conduct electricity in one direction but prevent conduction in the opposite one. They are found at the...
Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.
Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
19.11.2018 | Event News
09.11.2018 | Event News
06.11.2018 | Event News
21.11.2018 | Life Sciences
21.11.2018 | Power and Electrical Engineering
21.11.2018 | Life Sciences