Polymer-coated silicon nanosheets could be an alternative to graphene
Similar to carbon, silicon can form two-dimensional networks that are just one atomic layer thick. Much like graphene, these nanosheets exhibit excellent optical properties. In theory, it could be used in nanoelectronic applications. Besides for flexible display panels or field effect transistors, the material could also be a candidate for anodes in lithium ion batteries. “Silicon nanosheets are particularly interesting because today our entire information technology is based on silicon. For industrial applications, it would not require to change over to a new basic material – in contrast to graphene,” explains TUM researcher Tobias Helbich. “However, these nanosheets are very fragile and disintegrate quickly when under UV radiation, which greatly limits their application.”
Along with other researchers, Helbig for the first time succeeded in embedding silicon nanosheets into a polymer and thus protect it from disintegration. The embedding process has a two-fold effective on the nanosheets: They are chemically modified and at the same time protected against oxidation. The development from the TUM is the first nanocomposite based on silicon nanosheets.
“What makes our nanocomposite special is that it combines the positive properties of both of its components,” explains Helbich. “The polymer matrix absorbs light in the UV domain, stabilizes the nanosheets and gives the material the properties of the polymer, while at the same time maintaining the remarkable optoelectronic properties of the nanosheets.”Its flexibility and durability against external influences makes the newly developed material amenable to standard polymer technology for industrial processing. This puts actual applications within an arm’s reach.
The composites are particularly well suited for application in the up and coming field of nanoelectronics. Here, “classical” electronic components like circuits and transistors are implemented on scales of less than 100 nanometers. This allows whole new technologies to be realized – for faster computer processors, for example.
The first successful application of the nanocomposite was recently presented in the context of the ATUMS Graduate Program (Alberta / TUM International Graduate School for Functional Hybrid Materials): Alina Lyuleeva and Prof. Paolo Lugli from the Institute of Nanoelectronics at TUM, in collaboration with Helbich and his colleague Bernard Rieger, succeeded in building a photodetector based on these silicon nanosheets.
To this end, they mounted the polymer embedded silicon nanosheets onto a silicon dioxide surface coated with gold contacts. Because of its extreme small dimensions, this kind of nanoelectronic detector saves a lot of both space and energy.
The research is part of the ATUMS Graduate Program (Alberta / TUM International Graduate School for Functional Hybrid Materials (ATUMS; IRTG 2022)) in which German and Canadian scientists in the fields of chemistry, electrical engineering and physics collaborate. Their goal is not only to create novel functions based on nanoparticles and polymer materials, but, at the same time, to develop first applications. The work is funded by the German Research Council (DFG) and the Natural Science and Engineering Research Council of Canada (NSERC).
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