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New Technology For Converting a Metal To a Semiconductor With a Laser
rtoz writes "Researchers at MIT have succeeded in producing and measuring a coupling of photons and electrons on the surface of an unusual type of material called a topological insulator. This type of coupling had been predicted by theorists, but never observed. The researchers suggest that this finding could lead to the creation of materials whose electronic properties could be 'tuned' in real time simply by shining precise laser beams at them. This work opens up a new avenue for optical manipulation of quantum states of matter. Their findings suggest that it's possible to alter the electronic properties of a material — for example, changing it from a conductor to a semiconductor — just by changing the laser beam's polarization. For example, a property called a bandgap — a crucial characteristic for materials used in computer chips and solar cells — can be altered by shining a polarized laser beam at the material."
We've known about this since the turn of the last century. It's the photoelectric effect. Every material has a wavelength where if it is struck by a charged particle at or above that, it will absorb it and then emit an electron. This isn't news.
What's news is that we've now reached a sufficient level of understanding regarding the engineering of electro-optical systems that we are starting to build devices where the primary logic is based on optics, not electronics. This is an advancement of technology, not of understanding.
I am a bit confused by what you said. An incident photon at wavelength (Lamda) or smaller will eject an electron ( photo electric) and thermal excitation of a material like the cathode of a tube will also eject electrons. I am not getting where the charged particle comes in. From TFA:
In other situations, light can modify a material’s behavior — but only when it’s absorbed, transferring its energy to the material. In this experiment, Gedik says, the light’s energy is below the absorption threshold. This is exciting, he says, because it opens up the possibility of switching a material’s behavior back and forth without inducing other effects, such as heating — which would happen if the light were absorbed.
What they are talking about is changing the bandgap with the incident angle of polarized infrared laser light.
That's girlintraining's schtick. He comes in, makes some kind of pseudo-intellectual post full of wrongness, and the uneducated slobs mod him up. It really shows how uninformed the average slashdotter is.
no, this is not the photoelectric effect. the "bandgap" is range of energy levels where no electron exists. Thisproperty separates insulators, semiconductors and conductors. They are altering the bandgap with polarization of light
I'm very disappointed there's absolutely no mention of sharks in this article.
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