Organic thin film transistors with HfO2high-k gate dielectric grown by anodic oxidation or deposited by sol-gel

We report here on pentacene based organic field effect transistors (OFETs) with a high-k HfO
2
gate oxide. HfO
2
layers were prepared by two different methods: anodic oxidation and sol-gel. A comparison of the two processes on the electrical properties of OFETs is given. Ultra thin nanoporous (20 nm) sol-gel deposited oxide films were obtained following an annealing at 450°C. They lead to high mobility and stable devices (μ=0.12 cm
²
/V.s). On the other hand, devices with anodic HfO
2
revealed a little bit more leaky and show some hysteresis. Anodization, however, presents the advantage of being a fully room temperature process, compatible with plastic substrates.