Mechanism of resistive memory effect in Ga doped ZnO thin films

A hypothesis based on the model which explains the resistance change effect of resistive random access memory (ReRAM) by redox reaction is proposed. This hypothesis leads a conclusion that the relation between the polarity of the applied bias voltage and the caused resistance change in p-type semiconductors is opposite to that in ntype. Bias polarity dependence of resultant resistance change of ZnO and Ga-doped ZnO (GZO), which are ntype semiconductors, were investigated using conducting atomic force microscope (C-AFM). It was clarified that the opposite bias polarity is required to make GZO and NiO into the same resistance state, consistent with our hypothesis. In addition, enhancement of the resistance change effect by increasing Joule heating was observed. The present work also suggested that controlling the local carrier concentration of oxide films by application of localized strong electric field is possible. This technology might enable the fabrication of not only memory devices but also new nano-scale electronic devices.