[摘要]：We report on AC propagation in vertically stacked tri-layer nickel oxide (NiO) film with gradient in oxide composition. These studies reveal that the stacked film clips both positive and negative peaks of the AC signals and these clipping characteristics are analogous to a symmetrical clipper. These characteristics are obtained without using any clipper circuit elements like diodes or transistors and DC power source. We propose that the clipping characteristic of NiO stack is a result of space charge generated during signal propagation. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3703589]
