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Chemical Vapor Deposition Process Grows Versatile 2-D Material

Posted by Clayton Luz on Feb 28, 2017 10:30:00 AM

Researchers have produced a 2-D material called tungsten ditelluride, which they believe can have different properties instead of one, a dynamic known as topological electronic states.

 
Tungsten ditelluride is a transition metal dichalcogenide with physical and electronic properties that make it attractive for a variety of electronic applications.
 
Potential properties of the 2-D material include the ability to insulate, emit light, and can be spintronic, meaning they have magnetic properties.
 
The material 's multiple properties could also have implications in quantum computing, which might allow for an intrinsically error-tolerant form of quantum computing called topologically protected quantum computing, which requires both semiconducting and superconducting materials.  The process taps into the power of atoms and subatomic phenomena to perform calculations significantly faster than current computers, claim the scientists.
 
TUNGSTEN DITELLURIDE CREATED USING CHEMICAL VAPOR DEPOSITION PROCESS
 
A.T. Charlie Johnson and James Kikkawaand, both physics professors, and two graduate students—all of whom are affiliated with the University of Pennsylvania--were able to produce and measure the properties of a single layer of tungsten ditelluride.
 
The research team was able to grow the material using chemical vapor deposition. Using a hot-tube furnace, they heated a chip containing tungsten to the correct temperature and then introduced a vapor containing tellurium.
 
“Through good fortune and finding exactly the right conditions, these elements will chemically react and combine to form a monolayer, or three-atom-thick regions of this material,” Johnson says.
 
Because tungsten ditelluride is three atoms thick, the atoms can be arranged in different ways, he explains. “These three atoms can take on slightly different configurations with respect to each other. One configuration is predicted to give these topological properties.”
 
GRAPHENE REMAINS THE GOLD STANDARD
 
The most well-known 2-D material is graphene, a tightly packed, atomically thin sheet of carbon first produced in 2004. One of its most important properties is zero bandgap semiconductor in that it can behave as both a metal and a semiconductor.
 
“Graphene is just graphene,” Johnson notes. "It just does what graphene does. If you want to have functioning systems that are based on 2-D materials, then you want 2-D materials that have all of the different physical properties that we know about.”
 
Tungsten ditelluride grows in little rectangular crystallites unlike the triangles other materials grow in, the researchers discovered. Johnson explains this reflects the rectangular symmetry in the material, which has a "different structure so they tend to grow in different shapes.”
 
Although the research is still in its beginning stages and the researchers haven’t yet been able to produce a continuous film, they hope to conduct experiments to show that it has the topological electronic properties that are predicted.
 
Another property topological systems offer is that any current traveling through the material would only be carried on the edges instead of the current traveling through the center of the material. If researchers were able to produce single-layer-thick materials with this property, they may be able to route an electrical signal to go off into different locations.
 
 “With these 2-D materials, you want to realize as many physical properties as possible,” Johnson said. “Topological electronic states are interesting and they're new and so a lot of people have been trying to realize them in a 2-D material. We created the material where these are predicted to occur, so in that sense we've moved towards this very big goal in the field.”
 
The research findings were published in 2-D Materials.
 
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Topics: Manufacturing