Junctionless Coplanar-Gate Oxide-Based Thin-Film Transistors Gated by AluOa Proton Conducting Films on Paper Substrates

Nanogranular Al2O3 films deposited by plasma-enhanced chemical vapor deposition show a high proton conductivity of -1.25 × 10^-4 S/cm and a huge electric-double-layer （EDL） capacitance of -4.8μF/cm^2 at room temperature. Using nanogranular Al2O3 proton conducting films as gate dielectrics, junctionless indium-zincoxide （IZO） thin-film transistors （TFTs） with a coplanar-gate configuration are fabricated. The unique feature of such junctionless TFTs is that the channel and source/drain electrodes are the same thin IZO film without any source/drain junction. Due to the strong EDL capacitive coupling triggered by mobile protons in nanogranular Al2O3, these TFTs show a low-voltage operation of 1.5 V and a high performance with a large field-effect mobility （〉18cm2/V.s）, a small .subthreshold swing （〈130mV/decade） and a high current on/off ratio （〉 106）. Our results demonstrate that such junetionless TFTs gated by Al2O3 proton conducting films have great potential applications in low-power and low-cost electronics.