Effects of furnace annealing and hot pressing on the properties of SZO thin films and on the characteristics of SZO-TFTs

Abstract

Silicon zinc oxide (SZO) thin films were deposited via co-sputtering, while thin-film transistors (TFTfs) with the SZO film as the active layer were fabricated with a bottom gate configuration. Two kinds of post-treatment, furnace annealing and hot pressing, were carried out on the deposited SZO films. The effects of the post-treatment on the crystalline structure, chemical bond, surface roughness, and optical transmittance of the deposited SZO TFTs were analyzed as functions of the post-treatment conditions that were used. It was observed from the X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results that the structure of the SZO film became amorphous and the amount of Si-O bonds in the SZO film drastically increased after low-temperature furnace annealing. The on-off current ratio was 1.35 x 108 for the TFT after furnace annealing (200 degrees C) and 1.93 x 10(8) for the TFT after hot-pressing (200 degrees C, 2MPa), while that of the as-deposited SZO-TFT was 3.16 x 10(6). The experiment results showed that the hot pressing method would be preferable because it could improve the electrical characteristics of the SZO-TFTs, yielding similar results from the case where furnace annealing for about 60 min was carried out, in spite of the short process time (about 30 s) of the hot pressing method. (C) 2015 Elsevier B.V. All rights reserved.