By artificially creating one of nature’s strongest materials, researchers may have expanded the applications of the 2D material.
A team from the Columbia University, Princeton University, Purdue University and Istituto Italiano di Tecnologia, have engineered artificial graphene by recreating the electronic structure of graphene in a semiconductor device.
The artificial graphene allows the researchers to design variations into the honeycomb lattice to modulate electronic behavior.
“This milestone defines a new state-of-the-art in condensed matter science and nanofabrication,” Aron Pinczuk, Ph.D., a professor of applied physics and physics at Columbia, said in a statement. “While artificial graphene has been demonstrated in other systems such as optical, molecular, and photonic lattices, these platforms lack the versatility and potential offered by semiconductor processing technologies.
“Semiconductor artificial graphene devices could be platforms to explore new types of electronic switches, transistors with superior properties, and even, perhaps, new ways of storing information based on exotic quantum mechanical states,” he added.
Natural graphene only has one atomic arrangement where the positions of the atoms in the lattice are fixed. Experiments on graphene must therefore adapt to those constraints.
However, with artificial graphene the lattice can be engineered over a wide range of spacing and configurations that will allow for more versatile properties than the natural forming graphene.
“This is a rapidly expanding area of research, and we are uncovering new phenomena that couldn’t be accessed before,” Shalom Wind, Ph.D., faculty member of the department of applied physics and applied mathematics and co-author of the study, said in a statement. “As we explore novel device concepts based on electrical control of artificial graphene, we can unlock the potential to expand frontiers in advanced optoelectronics and data processing.”
The researchers developed the artificial graphene in a standard semiconductor material –gallium arsenide. They designed a layered structure where the electrons could move only within a very narrow layer, effectively creating a 2D sheet.
They used nanolithography and etching to create a hexagonal lattice of sites in which the electrons were confined in the lateral direction.
By placing the sites close to one another—about 50 nanometers apart—the artificial atoms could interact quantum mechanically, similar to the way atoms share their electrons in solids.
The researchers probed the electronic states of the artificial lattices by shining laser light on them and measuring the scattered light.
The scattered light showed a loss of energy that corresponded to transitions in the electron energy from one state to another and when they mapped these transitions, the team found that they were approaching zero in a linear fashion around the “Dirac point,” where the electron density vanishes, a hallmark of graphene.
The study was published in Nature Nanotechnology.
