Flexible InGaZnO-Based TFTs and Circuits on Clear Polyetherimide Substrate

Finding and evaluating thermally stable and optically clear plastic substrates for the fabrication of unobtrusive high-performance flexible electronics remains a challenge. Polyetherimide (PEI) is a candidate on which we present the fabrication, and characterization of IGZO thin-film transistors (TFTs), self-aligned devices, and an analog circuit. The TFTs exhibit state-of-the-art electrical performance with an effective mobility of 22 cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> V<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> s<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup>, an ON-OFF current ratio exceeding 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup>, and a threshold voltage of 2.8V. Their electrical stability was assessed through bias stress experiments, which revealed maximal threshold voltage shifts of only 0.6V after gate bias voltages of 5V were applied up to 5 h. In addition, the IGZO TFTs maintain their functionality when bent to a minimum radius of 15mm and are exposed to 1000 bending cycles. Finally, a fully integrated common source amplifier operated at a supply voltage of 5V demonstrated a voltage gain of ≈7.8 dB, a cutoff frequency of 19 kHz, and a power consumption of 15.5 μW. This illustrated the potential for PEI as a substrate for low-power wearable applications.