Nonvolatile Resistance Random Access Memory Devices Based on ZnO Nanorod Arrays

In this paper, a nonvolatile resistance random access memory (RRAM) device based on ZnO nanorod arrays has been fabricated and characterized. Vertically aligned ZnO nanorod layers (NRLs) were deposited on indium tin oxide (ITO) electrodes using a hydrothermal process/chemical bath deposition (CBD). It can be found the Ag/ZnO NRL/ITO capacitor exhibits bipolar resistive switching behavior. The resistive switching behavior may be related to the oxygen vacancies and/or zinc interstitials confined on the surface of the ZnO NRs, giving rise to the formation of straight and extensible conducting path along each ZnO NR. Furthermore, superior stability in resistive switching characteristics was also observed. Both growing times and annealing times were investigated and annealing was done in oxygen for 3, 6 and 9 minutes at different temperatures. For ZnO nanorods that had been annealed for 6 minutes the forming voltage was about 6.06V, the Set voltage was about 3.25V and the Reset voltage was -2.78V. The original resistance was 7x10(6)Omega. The resistance in the low-resistance state was 10(8)Omega and in the high-resistance state was 2016 Omega, the resistance ratio was 18.7.