Wavy Channel Thin Film Transistor

A new approach

Demonstration of a novel thin film transistor architecture, which improves ION per unit chip area by increasing the device width vertically without extra chip area penalty, as well as, enhances the field effect mobility, μFE, and thus gm per unit device width due to better electrostatics. This allows boosting performance of the smallest reliable Lg without changing VT or IOFF. The second objective of the project is to demonstrate low-temperature oxide based circuits that demonstrate the advantages of this novel architecture over the conventional planar architecture.

We have fabricated inverters, NOR, NAND, and pass-transistor logic multiplexers: Fabricated inverters show that WC inverters can achieve 2× the peak-to-peak output voltage for the same input when compared to planar devices. Also, WC inverters show 30% faster rise and fall times, and can operate up to ~2× frequency of the planar inverters for the same peak-to-peak output voltage. WC NOR circuits have shown 70% higher peak-to-peak output voltage, over their planar counterparts, and WC pass transistor logic multiplexer circuit has shown more than 5× faster high-to-low propagation delay compared to its planar counterpart at a similar peak-to-peak output voltage. Fabricated NAND circuits have shown 2× higher peak-to-peak output voltage for the same input voltage. They also have 3× lower high-to-low propagation delay times, respectively, when compared to the planar architecture. The performance enhancement is attributed to both extra device width and enhanced field effect mobility due to higher gate field electrostatics control.

So where to from here then?

1) Demonstration of the WC architecture on plastic substrates such as polyimide and Kapton sheets, and showing their potential for flexible display application.
2) Demonstration of analog circuits such as common source amplifiers, differential amplifiers and ring oscillators using the WC architecture.

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