Fabrication and characterization of micrometer-scale ZnO memristors

Memristors are an interesting class of resistive random access memory (RRAM) based on the electrical switching of metal oxide film resistivity . They are characterized for exhibiting resistive switching between a high-resistance state (HRS) and a low-resistance state (LRS) and have been recently considered as one of the most promising candidates for next-generation nonvolatile memory devices because of their low power consumption, fast switching operation, nondestructive readout, and remarkable scalability. The device structure is simply an oxide layer sandwiched between two metal electrodes. The switching behaviour is dependent both on the oxide material and the choice of metal electrodes. For this reason switching characteristics of many metal oxide films (e.g. TiO2, NiO, TaO2, HfO2) and metal contacts have been studied [1]. ZnO has attracted much attention as an oxide material for memristor application, due to its abundance in nature, which means low cost, and compatibility to CMOS technology in terms of process integration and device scalability down to nanometric sizes.In this work we report on resistive switching behaviour observed in microscale memristors based on laser ablated ZnO. Results show that devices up to 300 × 300 m exhibit a memristive behaviour regardless of device size, and 100 × 100 μm2 memristors have the best resistance off/on radio.