Low-temperature sol–gel processed AlOx gate dielectric buffer layer for improved performance in pentacene-based OFETs

Abstract

An approach to achieve improved performance in pentacene-based organic field effect transistors (OFETs) using high-k AlO_x prepared by a low temperature sol–gel technique as a thin buffer layer on a SiO₂ gate dielectric was demonstrated. The maximum processing temperature for the AlO_x thin layer was 150 °C. The resulting all-inorganic SiO₂/AlO_x bilayer gate dielectric system exhibited a low leakage current density <1 × 10⁻⁸ A cm⁻² under an applied electric field strength of 1.8 MV cm⁻¹, a smooth surface with an rms of 0.11 nm and an equivalent dielectric constant (k) of 4.13. The OFET fabricated as a result of this surface modification exhibited a significantly improved field effect mobility of 0.81 cm² V⁻¹ s⁻¹ when compared with a reference device with a SiO₂ single layer gate dielectric, which had a lower mobility of 0.28 cm² V⁻¹ s⁻¹.