Fire BAD!
Posted on 06/06/2017 9:40:56 AM PDT by Red Badger
A team of researchers at the Israel Institute of Technology has developed a new capacitor with a metal-insulator-semiconductor (MIS) diode structure that is tunable by illumination. The capacitor, which features embedded metal nanoparticles, is similar to a metal-insulator-metal (MIM) diode, except that the capacitance of the new device depends on illumination and exhibits a strong frequency dispersion, allowing for a high degree of tunability.
This new capacitor has the potential to enhance wireless capability for information processing, sensing and telecommunications. The researchers report their findings this week in the Journal of Applied Physics.
"We have developed a capacitor with the unique ability to tune the capacitance by large amounts using light. Such changes are not possible in any other device," said Gadi Eisenstein, professor and director of the Russell Berrie Nanotechnology Institute at the Technion Israel Institute of Technology in Haifa and a co-author of the paper. "The observed photo sensitivity of this MIS diode structure expands its potential in optoelectronic circuits that can be used as a light-sensitive variable capacitor in remote sensing circuits."
MIM diodes are common elements in electronic devices, especially those utilizing radio frequency circuits. They comprise thin-film metal plate electrodes that are separated by an insulator. Like the MIM structure, the researchers' new MIS capacitor is bias independent, meaning the constant capacitance is independent of its supply voltage. Bias-independent capacitors are important for high linearity, and therefore straightforward predictability, of circuit performance.
"We have demonstrated that our MIS structure is superior to a standard MIM diode," said Vissarion (Beso) Mikhelashvili, senior research fellow at the Israel Institute of Technology and also a co-author of the paper. "On one hand, it has all the features of an MIM device, but the voltage independent capacitance is tunable by light, which means that the tuning functionality can be incorporated in photonic circuits."
"The illumination causes a twofold effect," Eisenstein said. "First, the excitation of trap states enhances the internal polarization. Second, it increases the minority carrier density (due to photo generation) and reduces the depletion region width. This change modifies the capacitance."
The researchers created three MIS structures, fabricated on a bulk silicon substrate, based on a multilayer dielectric stack, which consisted of a thin thermal silicon dioxide film and a hafnium oxide layer. The two layers were separated by strontium fluoride (SrF2) sublayers in which ferrum (Fe, iron) or cobalt (Co) nanoparticles were embedded.
The researchers found that the fluoridation-oxidation process of the iron atoms causes the formation of a gradient in the valence state of iron ions across the active layer, which results in the generation of an electronic polarization. The polarization causes a bias-independent depletion region and hence an MIM-type characteristic.
Four additional structures were prepared for comparison: Two lacked the SrF2 sublayers and one of them was prepared without the iron film. The other two structures contained SrF2: One did not have cobalt and the second included a one-nanometer Co layer.
The comparison with other MIS capacitors that contained the metal nanoparticles with or without the SrF2 sublayers led to the unequivocal conclusion that only devices consisting of the combination of Fe and SrF2 turn the MIS structure into a photo-sensitive MIM-like structure.
More information: "Optical control of capacitance in a metal-insulator-semiconductor diode with embedded metal nanoparticles," Journal of Applied Physics (2017). DOI: 10.1063/1.4983760
Journal reference: Journal of Applied Physics
Technology Ping!..............
How will this make our lives better?
It will infiltrate everything, and you won't even notice it.
One small step to the flux capacitor!
So if you isolate it on the gate of a FET, you can use it as a photo switch. Photo switch and amplifier in one!
Elsewhere if has been written “This new capacitor has the potential to enhance wireless capability for information processing, sensing and telecommunications.”
So they can change the capacitance based simply on brightness, a capacitor dimmer switch.
Off the top of my head, would make it possible to make very low-noise optical tuned parametric amplifiers.
I haven't seen enough technical data to really be sure, but such devices could have significant effects in many areas of technology.
It's amazing how rapidly technological miracles become woven into the fabric of everyday life and essentially forgotten, except that they are used all the time.
For example, the computing and communications power in an iPhone, gigahertz information processors and multi-gigahertz radios, is amazing enough. But to run it for hours on a tiny battery, with minimal heat generation, is even more amazing.
Yet hundreds of millions of people who use the technology and benefit from it are completely unaware of it, take it for granted, except to complain about what it costs.
The same could be said for many other things, such as optical fibers, superalloys that make things like miniature earphones and tiny high-power motors possible, miniature TV cameras, etc.
This provides a direct optical to electronic interface so that results of optical calculations could be transmitted to electronic display devices or for further computation. It is actually a big deal.
I wonder when we will read "Arabic Institute of Technology has developed . . ." (cough)
I’m glad you’re on our side.
Don’t hold you breath.
Well, the guy is no Eisenstein...
I need a techno-geek to translate this into simpleton English.
“Yet hundreds of millions of people who use the technology and benefit from it are completely unaware of it, take it for granted, except to complain about what it costs.”
In a way I feel sorry for those people. There is a joy and awe that they are missing out on due to their unawareness. It’s similar to someone not being able to appreciate great works of art, literature, music.
It will make it far easier for the NSA to monitor us.
Fire BAD!
Scientists in Israel have developed a solid-state device that changes its capacitance according to the brightness of light falling on it.
This can be used in measuring devices for solar, optical or other light based research...................
I’m in for two of them for my Les Paul if they enable me to dial in Mike Bloomfield and Peter Green.
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