“In Dirac point. In practice, they behave as not having a gap at all., there is an energy region called the band gap where there are no available,” Foa Torres, at the in , told PhysOrg.com. “One says that the there is zero. If you have your device connected between two electrodes and it has no states available, then the electric current through it can be made very small. A zero-gap semiconductor, also called a gapless semiconductor, is a material where the density of electronic states vanishes at a single point. This is the case for , where the pi and pi* bands touch at a single point, the so-called
“Lacking a band gap means that graphene cannot be ‘switched-off,’” he explained. “Having ‘on’ and ‘off’ currents may encode information such as the 1’s and 0’s necessary for computing and is crucial for active electronic devices such as switches and transistors. This is the reason why having no band gap is one of the main drawbacks hindering many applications of this outstanding material.”
In a new study, Foa Torres and his coauthors have addressed this problem. By analyzing the way that afield interacts with electrons in graphene, the researchers have predicted that shining a mid-infrared laser on graphene can produce band gaps in its electronic structure. Further, the researchers predict that the band gaps could be tuned by controlling the laser polarization. As Foa Torres explained, the key to how “opens up” band gaps in graphene involves electrons interacting with the laser field.
“Imagine an electron moving, say from larboard to right, into a arena aflame by the laser field,” he said. “Then what happens is that the electron interacts with the radiation by arresting or abounding photons. This alternation leads to the electron actuality reflected or backscattered, as it would accept hit a wall: the bandage gap. In adverse with accepted bandage gaps, this one is dynamically produced by the laser.”
By assuming that a laser acreage could be acclimated to tune the cyberbanking anatomy of graphene, the abstraction has both axiological implications and abstruse applications.
“The coaction amid the appropriate cyberbanking anatomy of graphene and the laser may advice to abet alien states of amount such as topological insulators, abstracts that are insulators in the aggregate but appearance able-bodied advice in the surface,” Foa Torres said. “On the added hand, from an activated point of view, I accede that these laser-induced bandage gaps could accessible an access for a new brand of optoelectronic devices, accessories that transduce optical into electrical signals.”
For Foa Torres and his coauthors, the abutting acute footfall is beginning verification.
“Experimental analysis of our allegation is one of the capital active armament of our project,” he said. “With the aim of paving the way for experimentalists to be able to verify them, we accept performed a actual accomplished affability of ambit such as laser frequency, amplitude, etc. During the aftermost months we accustomed actual admired acknowledgment from top-level beginning groups in the US and Spain that are absorbed in our proposal. As always, there are absolutely still some issues to break afore it turns into absoluteness but one should go footfall by step. The aperture is now open, we are aloof entering a able terra incognita.”
- Singapore researchers invent broadband graphene polarizer (physicsinventions.com)