Flexible Electronics

A team of engineers from the University of Alberta (U of A) has developed a transistor that could be used to develop flexible electronic devices.

Thin film transistors (TFT) are commonly used for low-power, low-frequency devices such as screens. Over the years, researchers continue to seek ways to improve the technology being used for it, and what the electrical engineering team from U of A did was design new transistor architecture that uses bipolar action.

Quite simply, instead of using one type of charge carrier, which is what most thin film transistors do, it uses electrons and the absence of electrons (or holes) to add electrical output. A big step towards their success was them being able to form an ‘inversion’ hole layer in a ‘wide-bandgap’ semiconductor.

“[We] were [then] able to construct a unique combination of semiconductor and insulating layers that allowed us to inject “holes” at the MOS interface,” said Gem Shoute, a PhD student in the Department of Electrical and Computer Engineering who is lead author on the article.

Adding holes at the interface increased the chances of an electron “tunneling” across a dielectric barrier. Through this phenomenon, a type of quantum tunnelling, we were finally able to achieve a transistor that behaves like a bipolar transistor.”


The goal was to create a thin film transistor with the highest power handling and switching speed possible.

According to co-author Ken Cadien, “It’s actually the best performing [TFT] device of its kind—ever. This kind of device is normally limited by the non-crystalline nature of the material that they are made of.”

The size of the device can be scaled to improve performance to keep up with the miniaturization, a feature that today’s TFTs do not have, and has power-handling capabilities that is 10 times greater than any commercially available thin film transistors available today.

The team has already filed a provisional patent on the transistor. The next step involves putting it to work in one of its major areas of application.

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