A high-temperature resistant polyimide gate insulator surface-modified with a YOx interlayer for high-performance, solution-processed Li-doped ZnO thin-film transistors

Abstract

We report here a fully aromatic polyimide film with excellent electrical insulating properties and thermal stability. To use the polyimide as a gate insulator for high-performance solution-processed metal oxide thin-film transistors, the surface of a 350 nm thick polyimide film was modified with a 25 nm thick yttrium oxide interlayer. The YO_x/polyimide gate insulator showed excellent gate insulating properties with a dielectric constant of 3.2 at 10 kHz and a leakage current density of 3.3 × 10⁻¹⁰ A cm⁻² at 2 MV cm⁻¹ after the 300 °C annealing process. We prepared solution-processed Li-doped ZnO thin-film transistors with the prepared gate insulators. After the surface modification with the interlayer, the field-effect mobility of the 300 °C annealed Li-doped ZnO thin-film transistor increased from 0.1 cm² V⁻¹ s⁻¹ to 4.9 cm² V⁻¹ s⁻¹.