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)


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
Issue number27
Publication statusPublished - 2015 Jul 15


All Science Journal Classification (ASJC) codes

  • Materials Science(all)

Cite this