Technion makes revolutionary light source on single atomic layer
These findings can revolutionize technology development and can pave the way for a wide range of devices on an atomic scale.
By AARON REICHThe incorporation of a WSe2 monolayer into a photonic crystal slab with geometric phase defects enables spin-dependent manipulation of the emission from valley excitons of the WSe2, as well as from randomly placed quantum emitters.(photo credit: COURTESY TECHNION)
Scientists at Technion-Israel Institute of Technology have developed a new light source on just a single atomic layer of matter, which can potentially revolutionize technology development on an atomic level.As detailed in the findings published in the academic journal Nature Technology, the researchers were able to control the spin of photos emitted from two-dimensional matter through the interaction of a single atomic layer with nano-antenna arrays in a silicon chip.As explained in a statement by Prof. Elad Koren, head of Technion's Laboratory for Nanoscale Electronic Materials and Devices in the Department of Materials Science and Engineering whose team collaborated on the study, the research builds off the work pioneered in 2004 by renowned physicists Andre Geim and Kosntantin Novoselov, who discovered the material known as graphene and for which they later won the Nobel Prize in Physics in 2010.Their methodology for creating individual layers of carbon atoms was very simple, Koren explained, as the two simply used adhesive paper on a piece of graphite and peeled it layer by layer until just a single atomic layer remained, which is called graphene.This discovery didn't just show how to obtain a single atomic layer though, as it also showed just how different the properties of what is essentially two-dimensional matter (as it is just a single layer of atoms rather than multiple layers) compared to the same matter in its three-dimensional state.In fact, graphene is shown to be 100 times stronger than steel and has numerous widespread potential applications in a variety of technologies – and is actually being used by Texas-based Rice University and Israel's Ben-Gurion University of the Negev to develop an air filtration system to filter out COVID-19 particles.And far from being limited to graphite, this vastly different display of properties was true in the two-dimensional states of other materials, and this includes semiconductors."Standard electronic chips are based on silicon, which severely limits the development of the next generation of computers that require a combination of electronics and photonics, partly due to a lack of an essential condition called 'direct energy gap' in silicon," explained Prof. Erez Hasman, head of Technion's Atomic-Scale Photonics Laboratory, who also collaborated on the study."To our surprise, direct energy gap was discovered in two-dimensional semiconductors, which makes it possible to combine photonics and electronics at the nanometric scale, use them to produce light sources and active photonic devices, and pave the way for future generations of chips."The currently widespread approach to miniaturizing electronic chips while improving its processing speed and information transferred rate is what's known as spintronics. This means operations are performed on a spin, which is what characterizes the intrinsic electron rotation, rather than on the current of the electronics itself. However, Hasman established a new field known as spin-optics in 2001, which focuses on using the spin of photons to transmit and process information in photonic chips. This can be done by controlling the spin with optics ad a nanometer scale, known as nano-photonics.
And this approach is uniquely suited for two-dimensional semiconductors, as the broken inversion symmetry allows a new degree of freedom in the control of spin-selective light emissions. It is for this reason the researchers, led by Dr. Kexiu Rong and Dr. Bo Wang, created single atomic layers of the semiconductor Tungsten Selenide (WSe2) and used nano antennas to break the symmetry of its photonic spin.In addition, the researchers also created a two-dimensional photonic crystal made of silicon, which makes an energy gap in the spectrum of emissions in order to block optical emission channels from the material. This then led the researchers to create a light source from just a single atomic layer, which separated and distorted the photons emitted from the semiconductor. These findings can lead to combinations of spintronics and spin-optiocs in order to develop a wide range of devices on an atomic scale.
