Bendable Single Crystal Silicon Nanomembrane Thin Film Transistors with Improved Low-Temperature Processed Metal-Si Ohmic Contact by Inserting TiO 2 Interlayer

摘要

Bendable single crystal silicon nanomembrane thin film transistors (SiNMs TFTs), employing a simple method which can improve the metal-Silicon (Si) contact characteristics by inserting the titanium dioxide (TiO 2 ) interlayer deposited by atomic layer deposition (ALD) at a low temperature (90 °C), are fabricated on ITO/PET flexible substrates. Current-voltage characteristics of titanium (Ti)/insertion layer (IL)-Si structures demonstrates that they are typically ohmic contacts. X-ray photoelectron spectroscopy (XPS) results determines that TiO 2 is oxygen-vacancies rich, which may dope TiO 2 and contribute to a lower resistance. By inserting TiO 2 between Ti and n-Si, I ds of bendable single crystal SiNMs TFTs increases 3–10 times than those without the TiO 2 insertion layer. The fabricated bendable devices show superior flexible properties. The TFTs, whose electrical properties keeps almost unchanged in 800 cycles bending with a bending radius of 0.75 cm, obtains the durability in bending test. All of the results confirm that it is a promising method to insert the TiO 2 interlayer for improving the Metal-Si ohmic contact in fabrication of bendable single crystal SiNMs TFTs.