Prestress Driven Improvement in Fracture Behavior of in Situ Sputtered Zinc Oxide Thin Films on Stretched Polymer Substrates

Hong Rak Choi, Senthil Kumar Eswaran, Yong Soo Cho

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Flexible electronic devices need to survive bending or stretching operation without mechanical failure. If inorganic thin films are involved in the device structure, the evolution of cracks is a major challenge to overcome. Here, we report a novel way to substantially improve the fracture behavior of films that are based on intentional utilization of residual stress on the films by in situ sputtering on a stretched polymer substrate. The in situ sputtering combined with a stabilization stage yielded ZnO:Al thin films with a nearly 2-fold improvement in crack initiation strain, which indicates greater resistance to bending. The critical strain of the optimal ZnO:Al films was ∼1.83%, which is a significant improvement compared to the current tolerance value of ∼1%. This was accompanied by a ∼300% improvement in fracture energy. We attributed the improved fracture behavior to the presence of residual compressive stresses, which creates a barrier for crack formation by acting opposite to the applied bending strain.

Original languageEnglish
Pages (from-to)14654-14659
Number of pages6
JournalACS Applied Materials and Interfaces
Volume7
Issue number27
DOIs
Publication statusPublished - 2015 Jul 15

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All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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