Researchers at The University of Manchester and Shandong University in China have developed a nanoscale transistor that will be one step closer to enabling the creation of flexible televisions, phones, and tablets as well as ‘truly wearable’ smart tech.
The international team has created an ultrafast, nanoscale transistor – called a thin film transistor (TFT) – composed of an oxide semiconductor. The TFT is the first oxide-semiconductor based transistor that can operate at a benchmark speed of 1 GHz. This could make the next generation electronic devices even brighter, faster, and more flexible than earlier ones.
A TFT is a type of transistor typically used in an LCD. These can be found in most advanced devices with LCD screens such as smartphones, high-definition televisions, and tablets.
How do they function? The LCD features a TFT behind each and every pixel and they serve as separate switches that allow the pixels to alter state rapidly, making them switch on and off a lot more quickly.
But a majority of existing TFTs are silicon-based which are opaque, rigid, and expensive compared to the oxide semiconductor series of transistors which the collaborative team is developing. While oxide TFTs will enhance the picture on LCD displays, it is their flexibility that is even more remarkable.
Aimin Song, Professor of Nanoelectronics in the School of Electrical & Electronic Engineering, The University of Manchester, states: “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 seen fast development when compared to its silicon equivalent which is progressively close to some major limitations. Prof Song says there has been rapid progress in oxide-semiconductors in the past few years and widespread efforts have been made so as to boost the speed of oxide-semiconductor-based TFTs.
So much so selected oxide-based technology has already begun substituting amorphous silicon in certain gadgets. Prof Song thinks these recent developments have drawn commercialization a lot closer.
He added: “To commercialize 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 optimized, 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.”
Reference: The paper ‘Amorphous-InGaZnO Thin-Film Transistors Operating Beyond 1 GHz Achieved by Optimizing the Channel and Gate Dimensions’ has been published in IEEE Xplore 10.1109/TED.2018.2807621
Advanced materials - Research beacons at The University of Manchester