Strained Growth of Aluminum-Doped Zinc Oxide on Flexible Glass Substrate and Degradation Studies Under Cyclic Bending Conditions

Aluminum-doped zinc oxide (AZO) thin films have been used in low cost transparent conductive oxide (TCO) applications. For flexible electronics, the devices are subjected to cyclic bending during manufacturing and usage, which may lead to both electrical and optical degradation of TCO thin films. This paper was designed to investigate the effect of the strained growth and normal growth methods on the electrical and optical degradation under diverse cyclic bending conditions. The AZO thin films were deposited on a 100 μm thick Corning Willow Glass flexible substrate by using an RF-magnetron sputtering technique. The design of experiments technique was applied to analyze the significant factors that can affect the electrical and optical performance of AZO thin films. The experimental factors include growth methods, bending radius, and tension. From the analysis of the X-ray diffraction technique, the AZO thin films grown by the normal method have dominant (0 0 2) orientation, but the AZO thin films prepared by the strained growth method show other orientations, including (0 0 2) orientation. Although the strained growth method does change the AZO thin film properties, the strained growth method does not significantly improve the reliability of the AZO thin film after a 2000 cycle bending fatigue test.