Manchester breakthrough brings flexible screens one step closer

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Flexible televisions, tablets and phones, plus high-performance wearable smart technology have come one step closer thanks to a new nanoscale transistor created by researchers at The University of Manchester and Shandong University in China.

These products, which might have seemed like a pipedream a few years ago, are now close to becoming a reality thanks to a key breakthrough by the international team.

They created a new ultrafast, nanoscale thin film transistor (TFT) out of an oxide semiconductor. The TFT is the first oxide semiconductor that’s capable of operating at 1GHz, a speed that can make the next generation of electronic gadgets faster, brighter and more flexible.

TFTs are transistors that are typically found in (LCD) screens in smartphones, tablets and HD TVs.

LCD screens have a TFT behind each pixel. The TFTs act like individual switches allowing pixels to change state quickly, turning on and off rapidly.

Currently, these TFTs are silicon-based and they are opaque, rigid and expensive compared with the oxide semiconductors developed by the Manchester and China team.

The new oxide TFTs will improve picture quality slightly on LCD displays, but the flexibility is what makes this a key breakthrough for electronic product applications.

Aimin Song, Professor of Nanoelectronics in the School of Electrical & Electronic Engineering, The University of Manchester, explains: “TVs can already be made extremely thin and bright. Our work may help make TV more mechanically flexible and even cheaper to produce.

“But, perhaps even more importantly, our GHz transistors may enable medium or even high performance flexible electronic circuits, such as truly wearable electronics.

“Wearable electronics requires flexibility and in many cases transparency, too. This would be the perfect application for our research.

“Plus, there is a trend in developing smart homes, smart hospitals and smart cities – in all of which oxide semiconductor TFTs will play a key role.”

Oxide-based technology has already started to replace amorphous silicon in some gadgets. Professor Song believes that these developments have brought the commercialisation of the technology much closer.

He continued: “To commercialise oxide-based electronics there is still a range of research and development that has to be carried out on materials, lithography, device design, testing, and last but not the least, large-area manufacturing. It took many decades for silicon technology to get this far, and oxides are progressing at a much faster pace.

“Making a high-performance device, like our GHz IGZO transistor, is challenging because not only do materials need to be optimised, a range of issues regarding device design, fabrication and tests also have to be investigated. In 2015, we were able to demonstrate the fastest flexible diodes using oxide semiconductors, reaching 6.3 GHz, and it is still the world record to date. So we’re confident in oxide-semiconductor based technologies.”

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