Direct observation of conducting filaments on resistive switching of NiO thin films

The Hg/NiO/Pt capacitor with a Hg top electrode diameter of about 35 mu m showed the typical bistable resistive switching characteristic. After the removal of the Hg top electrode, we directly observed the formation and removal of filaments for a high resistive state (R(off)) and a low resistive state (R(on)) by conducting atomic force microscope (CAFM). CAFM images for R(off) and R(on) states directly exhibit evidence of the formation and removal of filaments on the surface, which supports well the filament model as a switching mechanism of resistive random access memory. (C) 2008 American Institute of Physics.