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Researchers create new semiconductors from a silicon-based compound

27 March 2015

Researchers have produced nanostructures from silicon telluride that are pure, p-type semiconductors suitable for use in a variety of electronic and optical devices.

Chemists from Brown University have come up with a way to make new nanomaterials from a silicon-based compound, which can be made in a variety of morphologies (image: Koski lab/Brown University)

"Silicon-based compounds are the backbone of modern electronics processing," said Kristie Koski, assistant professor of chemistry at Brown University, who led the work. "Silicon telluride is in that family of compounds, and we've shown a totally new method for using it to make layered, two-dimensional nanomaterials."

Koski and her team synthesised the new materials through vapour deposition in a tube furnace. When heated in the tube, silicon and tellurium vaporise and react to make a precursor compound that is deposited on a substrate by an argon carrier gas. The silicon telluride then grows from the precursor compound.

Different structures can be made by varying the furnace temperature and using different treatments of the substrate. By tweaking the process, the researchers made nanoribbons that are about 50 to 1,000 nanometres in width and about 10 microns long. They also made nanoplates flat on the substrate and standing upright.

"We see the standing plates a lot," Koski said. "They're half hexagons sitting upright on the substrate. They look a little like a graveyard."

Each of the different shapes has a different orientation of the material's crystalline structure. As a result, they all have different properties and could be used in different applications.

The researchers also showed that the material can be 'doped' to change its electrical properities. In this case, the researchers showed that silicon telluride can be doped with aluminium when grown on a sapphire substrate. That process could be used, for example, to change the material from a p-type semiconductor to an n-type.

The materials are not particularly stable in the environment, but Koski says that's easily remedied. "What we can do is oxidise the silicon telluride and then bake off the tellurium, leaving a coating of silicon oxide. That coating protects it and it stays pretty stable. We think this is a good candidate for bringing the properties of 2D materials into the realm of electronics."

The work is published in the journal, Nanoletters

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