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

Amorphous In-Ga-Zn-O (a-IGZO) experiences an inherent structural instability which restrict its applications in electronic devices. By utilizing an in-situ mechanical stress analysis, we characterized the phase and structural changes. The glass transition temperature, T-g (423-562 degrees C) and fragility (18-28) in a-IGZO films were observed to ascertain quantitative criteria for the structural stability. The structural stability near T-g was significantly reduced as the thickness decreased due to the effect of the unstable surface layer. The structural relaxation of glass below T-g was identified as the viscous flow and densification. (C) 2014 The Electrochemical Society. All rights reserved.