Flexible Oxide-Based Thin-Film Transistors on Plastic Substrates for Logic Applications

Phosphorus doped (P-doped) nanogranular SiO2 films have been deposited by plasma-enhanced chemical vapor deposition. A high proton conductivity of ∼3.2 × 10−4 S/cm and a large electric double layer (EDL) capacitance of ∼3.2 μF/cm2 have been obtained. Flexible coplanar-gate EDL thin film transistors (TFTs) gated by P-doped nanogranular SiO2 films are self-assembled on plastic substrates at room temperature. Due to the big EDL capacitance, such TFTs show ultra-low voltage operation of 1 V, a large field-effect mobility of 18.9 cm2/Vs, a small subthreshold swing of 85 mV/decade and a high current on/off ratio of 107. Furthermore, the EDL TFT could work in dual coplanar gate mode. AND logic operation is realized. Our results demonstrate that such TFTs gated by P-doped nanogranular SiO2 films have potential applications in low-power flexible electronics.