Nano-pixels to bring flexible, high-res displays
Oxford University scientists have looked into the link between the electrical and optical properties of phase change materials (materials that can change from an amorphous to a crystalline state). They discovered that by sandwiching a 7nm thick layer of a phase change material (GST) between two layers of a transparent electrode, they could use a tiny current to 'draw' images within the sandwich 'stack'.
Initially still images were created using an atomic force microscope but the team went on to show that such tiny 'stacks' can be turned into prototype pixel-like devices. These nano-pixels, just 300 x 300nm in size, can be electrically switched 'on and off' at will, creating the coloured dots that would form the building blocks of an extremely high-resolution display technology.
Whilst the work is still in its early stages, realising its potential, the Oxford team has filed a patent on the discovery with the help of Isis Innovation, Oxford University's technology commercialisation company. Isis is now discussing the displays with companies who are interested in assessing the technology, and with investors.
Still images drawn with the technology: at around 70 micrometres across each image is smaller than the width of a human hair.
"We didn't set out to invent a new kind of display," said Professor Harish Bhaskaran of Oxford University's department of materials, who led the research. "We were exploring the relationship between the electrical and optical properties of phase change materials and then had the idea of creating this GST 'sandwich' made up of layers just a few nanometres thick. We found that not only were we able to create images in the stack but, to our surprise, thinner layers of GST actually gave us better contrast. We also discovered that altering the size of the bottom electrode layer enabled us to change the colour of the image."
The layers of the GST sandwich are created using a sputtering technique where a target is bombarded with high energy particles so that atoms from the target are deposited onto another material as a thin film.