Improvement of metal-oxide films by post atmospheric Ar/O2 plasma treatment for thin film transistors with high mobility and excellent stability

Abstract

Metal-oxide thin-film transistors (MO TFTs) with suitable device performances such as high field-effect mobility (μ FE), low subthreshold swing, high ON/OFF current ratio, and excellent stability under bias stress are of increasing attention for the applications to displays and flexible electronics. Here, we introduce the effect of post atmospheric Ar/O2 plasma (AAP) on spray-pyrolyzed MO film and its role in realizing the high-performance TFT. To better understand the physicochemical mechanism, the spectroscopic, morphologic, and electrical properties of the MO films were studied. From the X-ray photoelectron spectroscope (XPS) results, the composition ratios for Zn:La:O in AAP-treated LaZnO are 4.97:1.00:7.65 before treatment, 5.01:1.00:8.58 upon 5 cycles treatment, and 4.68:1.00:9.72 for 10 cycle treatment. The LaZnO TFT mobilities for 0, 5 and 10 cycles treatment are 8.64, 20.13, and 8.96 cm2 V−1 s−1, respectively. The AAP-treatment on the MO layer could improve the saturation mobility of ZnO, LaZnO, HfZnO, and LiZnO TFTs from 11.65, 8.95, 4.46, and 33.50 cm2 V−1 s−1 to 23.64, 20.13, 12.56, and 48.47 cm2 V−1 s−1, respectively. Furthermore, the optimal TFT shows excellent stability under positive (negative) bias temperature stress (PBTS and NBTS) with a negligible threshold voltage shift.