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Researchers Create First Silicene Transistor

An international team of scientists led by Dr Li Tao from the University of Texas at Austin, Texas, has created the first transistor made of silicene, the world’s thinnest silicon material.

Silicene transistor: Vg, Vs and Vd are the gate, source and drain voltages. Image credit: Li Tao

Silicene transistor: Vg, Vs and Vd are the gate, source and drain voltages. Image credit: Li Tao

Made of a one-atom-thick layer of silicon atoms, silicene has outstanding electrical properties but has until now proved difficult to produce and work with.

Dr Tao and his collaborators solved one of the challenges surrounding silicene by demonstrating that it can be made into transistors. These devices could pave the way for future generations of faster, energy-efficient computer chips.

Until a few years ago, artificial silicene was a purely theoretical material. Looking at carbon-based graphene, scientists speculated that silicon atoms could be structured in a broadly similar way.

“Apart from introducing a new player in the playground of two-dimensional materials, silicene, with its close chemical affinity to silicon, suggests an opportunity in the road map of the semiconductor industry,” said Dr Deji Akinwande of the University of Texas at Austin, the senior author on the study published in the journal Nature Nanotechnology.

“The major breakthrough here is the efficient low-temperature manufacturing and fabrication of silicene devices for the first time.”

Despite its promise for commercial adaptation, silicene has proved extremely difficult to create and work with because of its complexity and instability when exposed to air.

To work around these issues, the scientists let a hot vapor of silicon atoms condense onto a crystalline block of silver in a vacuum chamber.

They then formed a silicene sheet on a thin layer of silver and added a nanometer-thick layer of alumina on top.

Because of these protective layers, the researchers could safely peel it of its base and transfer it silver-side-up to an oxidized-silicon substrate.

They were then able to gently scrape some of the silver to leave behind two islands of metal as electrodes, with a strip of silicene between them.

The team will continue to investigate new structures and methods for creating silicene, which may lead to low-energy, high-speed digital computer chips.

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Li Tao et al. Silicene field-effect transistors operating at room temperature. Nature Nanotechnology, published online February 02, 2015; doi: 10.1038/nnano.2014.325