The devices, created with Shandong University in China, are made on a high-resistance silicon substrate using Ta2O5 gate dielectric. The material is 80% transparent, opening the door to display applications.
“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,” said Professor Aimin Song of Manchester’s School of Electrical & Electronic Engineering, adding: “In 2015, we were able to demonstrate the fastest flexible diodes using oxide semiconductors, reaching 6.3GHz, and it is still the world record to date. So we’re confident in oxide-semiconductor based technologies.”
Mobility of 18.2cm2/V/s was seen in the transistor’s carriers, with current gain and power gain cut-off at 1.24 and 1.14 GHz respectively, according to the IEEE Xplore paper paper ‘Amorphous-InGaZnO thin-film transistors operating beyond 1 GHz achieved by optimizing the channel and gate dimensions‘.
“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,” said Song.