Structural Instability in Amorphous In-Ga-Zn-O Films Investigated by Mechanical Stress Analysis

Abstract

The use of amorphous materials as key functional materials in various electronic devices continues to increase because they exhibit superior flexibility, adequate processability and reasonable performance. However, because the amorphous phase is metastable structure compared with the crystalline phase, its properties may drift over time and cause instability when applied in devices. Therefore, an understanding of the structural stability of amorphous materials is a key step in the fabrication of stable electronic devices. Amorphous In-Ga-Zn-O (a-IGZO) has been actively employed in electronic applications due to its high electron mobility and high stability of amorphous structure. 1 However, if a-IGZO is utilized as a thin film structure in electronic applications, high structural stability of a-IGZO can be hindered by the effect of surface. As thinner the film, higher the surface-to-volume ratio in film, therefore effect of the surface instability will be more significant: unconstrained bonds in surface are reported to be in high mobility of atoms, 2 and distinct coordination distributions in surface of amorphous Al2O3 films affect