The goal of this research is to develop flexible high voltage thin-film transistors (HVTFT) operating at > 500 V to drive arrays of high-voltage dielectric elastomer actuators (DEAs) and to interface triboelectric sensors and generators.
For high-speed and low power consumption, standard TFTs are fabricated with a high-K, thin dielectric (10s nm thickness range), consequently operating at drain-source voltage < 10 V and breaking down at low voltage.
Our approach is to use high-breakdown field, thick (> 100 nm) dielectric and shift the gate electrode location from the drain to achieve HVTFT operating at drain-source voltage > 500 V. We implement metal oxides alloys as the HVTFT thin-film semiconductor because of their high electron mobility, their tunability and their printability. The ultimate goal of this project is the printing of these high-voltage TFTs on polymeric and eventually elastomeric substrates.
We have achieved high-voltage thin film transistors on polyimide using zinc-tin oxide as the channel semiconductor, and a bilayer of ALD Alumina (100 nm) and Parylene-C (1 µm) as gate dielectric. The HVTFT operates at 1 kV and are flexible with a radius of curvature down to 2.5 mm. We demonstrated the driving of arrays of 1kV DEAs by integrating HVTFTs (https://www.epfl.ch/labs/lmts/DEAwithTFT)
These HVTFTs could be used as switches to drive high-voltage devices such as multiple degrees of freedom soft robots, haptic displays and microfluidic valves. We are also exploring their interfacing with high voltage triboelectric sensors and generators.
Our research covers:
- Transistors materials and design, processing, characterization;
- Modeling of the high-voltage effects by Spice and FEM methods;
- Development and characterization of solution processed metal oxide thin-film; semiconductor adapted for high-voltage applications;
- Development of a fully printed process;
- Application and integration with dielectric elastomer actuators and triboelectric generators technologies.
Contact: Dr. Danick Briand
References
- A. Marette, R. Haque, X. Ji, R. Hinchet, H. Shea, B. Briand, Triboelectric-TFT flip-flop for bistable latching of dielectric elastomer actuators, Adv. Electron. Mater. 2019, 1900205.
- H. Shea, D. Briand, Yttrium zinc tin oxide high voltage thin film transistors, Applied Physics Letters, 113, 132101 (2018); doi: 10.1063/1.5048992
- A. Marette, A., Poulin, A., Besse, N., Rosset, S., Briand, D., & Shea, H. Flexible Zinc–Tin Oxide Thin Film Transistors Operating at 1 kV for Integrated Switching of Dielectric Elastomer Actuators Arrays. Advanced Materials, 2017.