Scientists have developed what they believe is the thinnest-possible semiconductor, a new class of nanoscale materials made in sheets only three atoms thick.
The University of
"Heterojunctions are fundamental elements of electronic and photonic devices," said senior author
The research was published online this week in Nature Materials.
The researchers discovered that two flat semiconductor materials can be connected edge-to-edge with crystalline perfection. They worked with two single-layer, or monolayer, materials - molybdenum diselenide and tungsten diselenide - that have very similar structures, which was key to creating the composite two-dimensional semiconductor.
Collaborators from the electron microscopy center at the University of
The researchers created the junctions in a small furnace at the UW. First, they inserted a powder mixture of the two materials into a chamber heated to 900 degrees Celsius (1,652 F). Hydrogen gas was then passed through the chamber and the evaporated atoms from one of the materials were carried toward a cooler region of the tube and deposited as single-layer crystals in the shape of triangles.
After a while, evaporated atoms from the second material then attached to the edges of the triangle to create a seamless semiconducting heterojunction.
"This is a scalable technique," said Sanfeng Wu, a UW doctoral student in physics and one of the lead authors. "Because the materials have different properties, they evaporate and separate at different times automatically. The second material forms around the first triangle that just previously formed. That's why these lattices are so beautifully connected."
With a larger furnace, it would be possible to mass-produce sheets of these semiconductor heterostructures, the researchers said. On a small scale, it takes about five minutes to grow the crystals, with up to two hours of heating and cooling time.
"We are very excited about the new science and engineering opportunities provided by these novel structures," said senior author
The researchers have already demonstrated that the junction interacts with light much more strongly than the rest of the monolayer, which is encouraging for optoelectric and photonic applications like solar cells.
Other co-authors are
This research was funded by the
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