The new material could provide us with faster, higher-resolution displays. Researchers
All displays are made up of pixels whose brightness iscan be adjusted individually. Total number of pixels – and therefore the resolution and display size – limited by how many pixels can be processed in a given fraction of a second. Therefore, display manufacturers try to use materials in pixel control units that exhibit very high “electron mobility,” which is a measure of how quickly current will flow through such a control unit in response to the application of voltage – and thus how "fast" is a pixel.
ITZO promises to be seven times faster than today's similar materials. However, until now it has not been clear where this improvement comes from, which has prevented its application in industry.
Hokkaido University materials scientist Hiromichi Ohtaand his team used their unique measurement technique to clarify this issue. They showed that the higher electron mobility results from the unusual fact that, in ITZO films of sufficient thickness, free charges build up at the interface with the carrier material and thus allow passing electrons to pass unhindered through the bulk of the material.
According to them, it all comes down to a very simpleformula: Electron mobility is proportional to the free travel time of charge carriers – in this case electrons – divided by their effective mass. Ohta's team was able to determine the effective mass of the electrons and then calculate the free path time. It turned out that the effective mass is much smaller than that of modern materials, and the free travel time is much longer, and, therefore, both factors contribute to higher electron mobility.
“Using the knowledge gained during thisresearch, we may in the future develop other transparent oxide semiconductor thin film transistors with different chemistries that will exhibit even better electron mobility properties,” explains Ohta.