Low-cost nanomesh infrared photodetectors fabricated on paper. Photo: Dr Meng You, City University of Hong Kong.
Low-cost nanomesh infrared photodetectors fabricated on paper. Photo: Dr Meng You, City University of Hong Kong.

A collaborative team led by researchers from the City University of Hong Kong (CityU) has invented an innovative method for synthesizing high-quality, semiconducting nanomesh at a lower temperature and production cost than conventional methods. Their findings will help bring about the large-scale production of nanomesh for next-generation electronics.

Nanomesh is a nanoscale material formed from a network of nanowires. For several decades, one-dimensional materials like nanowires made of crystalline inorganic materials have been widely explored as the main driver for emerging electronics, as they have features like mechanical flexibility, energy efficiency and optical transparency. However, the scalability, integrability and cost-effectiveness of nanowire semiconductors have proved insufficient, limiting their potential for large-area electronic and optoelectronic applications.

To overcome these shortcomings, a research team led by CityU researchers has made a breakthrough, by inventing a low-temperature, vapour-phase growth method that can achieve large-scale synthesis of semiconducting tellurium (Te) nanomesh for use in electronic devices. The researchers report their breakthrough in a paper in Nature Communications.

"The use of tellurium nanomesh in electronics holds great promise for meeting the emerging technological demands of today’s Internet of Things (IoT) applications," said Johnny Ho, associate head and professor in the Department of Materials Science and Engineering (MSE) at CityU, who led the study. “The progress made in this research marks a significant step towards the large-scale production of functional tellurium nanomesh, enabling potential applications that are not achievable through other means.”

The newly developed method can produce high-quality tellurium nanomesh on various substrates, including silicon oxide, polymers (stretchable plastics) and even paper, in a scalable and cost-effective manner.

To initiate the growth process, tellurium source powders are first vaporized and carried to growth substrates, and then heated at 100°C with a flow of argon gas. By taking advantage of multiscale van der Waals interactions between the materials, the research team successfully created nanomeshes composed of self-assembled and self-welding tellurium nanowires. These nanomeshes were laterally vapour-grown on arbitrary surfaces at the low temperature of 100°C, which is impossible using conventional methods.

Since a much lower temperature than normal is required, and the nanomesh can be grown on various substrates, the production cost is lower. Also, the discovery of a self-welding process in the growth of tellurium nanomesh is crucial for improving device performance and ensuring the mechanical robustness of flexible electronics.

In experiments, the researchers demonstrated multi-functional applications for the tellurium nanomesh, including the capacity for micrometer-level patterning, the fabrication of high-mobility transistors, and the production of fast and sensitive infrared photodetectors (photoresponse time under 3µs) on paper.

“All the obtained device metrics are on par with state-of-the-art devices but can be produced at a lower cost. They are promising for meeting emerging technological demands,” said Ho. “This latest development has improved the transport and photoelectric properties of nanomesh and resolved concerns about the compatibility between the target device substrate and the nanomesh growth process. As a result, devices can now be produced on a wide range of technologically functional surfaces in a scalable and cost-effective manner.”

This story is adapted from material from the City University of Hong Kong, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.