A solution-processed silicon oxide gate dielectric prepared at a low temperature via ultraviolet irradiation for metal oxide transistors

Abstract

A facile route for the preparation of a solution-processed silicon oxide dielectric from perhydropolysilazane (PHPS) at a low temperature (≤150 °C) is proposed. Deep ultraviolet (DUV) irradiation on the PHPS-derived silicon oxide film, where the coupling agent of vinyltriethoxysilane (VTES) was introduced to assist the formation of the Si–O lattice network at a low temperature, allowed the prepared silicon oxide film to have device-quality insulating properties. The metal/insulator/metal capacitor with DUV-annealed silicon oxide exhibited a low gate leakage current density of 7.0 × 10⁻⁸ A cm⁻² at 1 MV cm⁻¹, which was attributed to the photon-assisted purification and densification of the silicon oxide film. The suitability of this silicon oxide film as a gate insulator was evaluated in all-solution-processed indium zinc oxide (IZO) thin-film transistors (TFTs). The IZO TFTs that were fabricated at a contact annealing temperature of 150 °C exhibited a high field-effect mobility of 17.3 cm² V⁻¹ s⁻¹, a threshold voltage of 2.7 V, and an I_ON/OFF modulation ratio of 1 × 10⁵. Therefore, DUV-assisted IZO TFTs with a PHPS-derived silicon oxide insulator are promising candidates for low-temperature, large-area, and flexible electronics for use on inexpensive plastic substrates.