Polish-Chinese team makes gold nanoparticle transistors

A team led by Professor Bartosz Grzybowski (Institute of Organic Chemistry PAS and Korean UNIST) and Professor Yong Yan (University of Chinese Academy of Sciences, Beijing) have shown how to make transistors from gold nanoparticles that are resistant to bending, water and sparks, and applied like paint, unlike traditional semiconductor materials.

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Until now, the construction of transistors, commonly used in everyday use devices, required semiconductor materials like germanium, silicon, gallium nitride and silicon carbide. Semiconductors have so-called band structure - they have conduction bands, thanks to which the current does not flow through them as obviously as, for example, through metals. This current flow can be modulated. Traditional semiconductors are not resistant to bending, moisture or electrical discharges, they have to be applied to the surface in a vacuum, and the semiconductors themselves crystalised at high temperatures.

“We show that it is possible to make a transistor and an integrated circuit not with a traditional semiconductor, but with a metal, this has not been obvious to physicists. Although the material is a metal, the ions moving around it can create local electric fields and cause effects similar to those in semiconductors,” Professor Grzybowski said. He added that metals can behave like semiconductors as long as it happens at the nanoscale thanks to achievements in chemoelectronics.

“Our transistor can be bent and nothing will happen to it. You can immerse it in a humid atmosphere or subject it to strong electric discharges and it will continue to work, because moisture is favourable to it and sparks do not damage it. Applying layers is simple: it consists of taking a mixture with nanoparticles and pouring it onto the surface. The solvent evaporates and a thin layer of nanoparticles adheres to the surface. It’s like applying paint. No vacuum or high temperatures are needed,” Professor Grzybowski said.

Although the new solution is unlikely to replace traditional semiconductor processors in computers, the new transistors could be used, for example, in applications under water or in a corrosive environment. In addition, the scientist says, perhaps these systems could be used as sensors for certain chemicals.