Innovations are being introduced to provide us with a new material with faster and higher resolution displays. Researchers at Hokkaido University were able to explain what makes this material unique, opening the way for its inclusion in further development.
All screens are made up of a network of tiny light points, called pixels, whose brightness can be controlled individually. The total number of pixels, and therefore the resolution and display size, is limited by the number of pixels that can be addressed in a fraction of a second. Therefore, display manufacturers are trying to use the material in the driver pixel that exhibits a high “electrical change”, which is an example of how quickly the current will begin to flow through one the unit. How “quick” is a pixel?
The new material called “ITZO” (for its composition of indium, tin, zinc and oxygen) promises to run seven times faster than the current state-of-the-art. However, the origin of this enhancement is unclear, limiting its adoption for industrial applications.
Hokkaido University materials scientist Hiromichi Ohta and his team used their unique measurement method to clarify the point. In their recent paper published in the journal Applied Electronic Materials, they showed that the high electron mobility results from the unusual fact that in perfect ITZO films, free charges accumulate at the interface and things that carry it and thus allow electrons to pass through. many things do not prevent it.
The special capacitance of one circle Ohta comes with a very simple formula: the mobility of electrons is equal to the free travel time of the charge that is carried – electrons in this case – divided by their effective mass. And although the observation of the electron movement itself is a common method, the effective ratio and free travel time cannot be measured as easily, so it is difficult to say which causes electron mobility.
But by measuring how the electrical current inside the material changes in response to an applied magnetic field and temperature gradient, Ohta’s team was able to extract the effective mass of electrons and calculate the free-travel time. It turns out that the effective number is smaller than that of the current elements and the free travel time is higher, so the two elements make the electron mobility higher. Also, by looking at how their results depend on the thickness of the ITZO material, they can deduce how the interface and volume of the material contribute to these effects.
Ohta explains the importance of this research: “Using the insights we gained from this study, we can in the future design transparent oxide semiconductor thin film transistors with different chemical properties that exhibit even more properties and – mobility.” Therefore, this study is a big step forward to the next generation of ultra-high resolution displays.
