Optimization of an Amorphous In-Ga-Zn-Oxide Semiconductor for a Top-Gate Transparent Thin-Film Transistor

We developed methods for a process optimization of amorphous In-Ga-Zn-oxide (IGZO, atomic ratio of the IGZO target lozenge In: Ga: Zn = 1 : 1 : 1) for transparent thin-film transistors (TTFTs). During the sputtering process, the ratio of oxygen to the total gas mixture could be chosen in order to obtain better electronic properties, depending on both the RF power and the sputtering pressure. The post-anneal treatment at 300 degrees C for 1 hour in an O-2 ambient was the most suitable condition for the interface between the IGZO channel and the Al2O3 gate insulator Finally, the introduction of a first step (FS) during the deposition was very effective in improving the electronic properties of the top-gate IGZO-TTFTs. Through these optimization methods, we achieved a field effect mobility of 11.7 cm(2)/sV, a sub-threshold-swing of 0.36 and a drain current on-off ratio of similar to 10(8) in the top-gate IGZO-TTFT.