[16] 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 35𝜇m 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.