Abstract
In this work, reactively sputtered TiO 2 films were reported to contain reduced Ti ions, the concentration of which correlates to the conductive channels formed in the film through percolation. Cells made on these films appear with different switching behaviors, depending on whether the as-fabricated cell intercepts the conductive channels. Films with a high population of conductive channels are "forming free" because most of the devices fabricated on them may intercept conductive channels and initially appear in the low resistance state. © 2009 The Electrochemical Society.