Low-temperature rapid preparation of high-performance indium oxide thin films and transistors based on solution technology

Abstract

Indium oxide (In<sub>2</sub>O<sub>3</sub>) thin films and thin-film transistors (TFTs) based on the solution process are prepared by pulsed UV-assisted thermal annealing at a low temperature (200 ℃) for 5 min. The effects of pulsed UV-assisted thermal annealing on the surface morphology, chemical structure, and electrical properties of the In<sub>2</sub>O<sub>3</sub> thin films are investigated, and they are compared with those of conventional thermal annealing (300 ℃, 30 min). The experimental results show that the pulsed UV-assisted thermal annealing method can improve the quality of In<sub>2</sub>O<sub>3</sub> thin film and the performance of TFT in a short period. The results of atomic force microscopy and field emission scanning electron microscopy show that the surface of the In<sub>2</sub>O<sub>3</sub> film is denser and flatter than that of the conventional thermally annealed film, and X-ray photoelectron spectroscopy tests show that the pulsed UV-assisted thermal annealing process generates oxygen vacancies, which increases the carrier concentration and improves the electrical conductivity of the In<sub>2</sub>O<sub>3</sub> film. In addition, the effect of pulsed UV-assisted thermal annealing on the electrical characteristics of In<sub>2</sub>O<sub>3</sub> TFTs is investigated in a comparative way. The results show that the electrical characteristics of the device are significantly improved: the subthreshold swing decreases to 0.12 mV/dec, the threshold voltage is 7.4 V, the current switching ratio is as high as 1.29×10<sup>7</sup>, and the field effect mobility is enhanced to 1.27 cm<sup>2</sup>·V<sup>–1</sup>·s<sup>–1</sup>. Therefore, pulsed UV-assisted thermal annealing is a simple and fast annealing method, which can rapidly improve the performances of In<sub>2</sub>O<sub>3</sub> thin film and TFTs, even under low-temperature conditions.