In situ electrical and mechanical study of Indium Tin Oxide films deposited on polyimide substrate by Xe ion beam sputtering

Four series of Indium Tin Oxide (ITO) thin films 600 nm thick were deposited on polyimide substrates by Xe ion beam sputtering under different deposition conditions: with or without O-2 flow, and at room temperature or 100 degrees C heated substrates. Both electrical and mechanical properties of the four different films were investigated in situ by electrical resistance measurements and synchrotron x-ray diffraction during equibiaxial deformation tests. The ITO films are found to have a low elastically anisotropy, i.e. an elastic anisotropy index slightly smaller than 1. The elastic regime domain is quite small and is associated to a small effective negative gauge factor. During biaxial straining, electrical measurements show that all films are very brittle with crack onset strains corresponding to applied strains ranging from 0.15 to 0.3%. The introduction of oxygen flow during deposition delays the crack onset as the decrease of deposition temperature does.