Thickness scaling effects of self-assembled NiO nanodots on resistive switching characteristics

Abstract

High-density resistive random access memory devices benefit from the reduction in the size of memory cells to a nanoscale. As the RRAM cells become smaller and denser, more stable operation is required. In this study, resistive switching characteristics of self-assembled NiO nanodots on Nb-doped SrTiO3 substrates were examined by using conducting atomic force microscopy. For the NiO nanodot thickness of 8, 6, and 4 nm, the forming voltages were 5.43, 4.63, and 4.12 V, respectively, indicating that the forming voltage decreased as the thickness of NiO nanodots decreased. The SET and RESET voltages also decreased (2.40 and 1.21 V for 8 nm, 2.11 and 0.96 V for 6 nm, 1.86 and 0.82 V for 4 nm, respectively). In addition, as the thickness of the NiO nanodots decreased, the distribution of forming voltages stabilized. We propose that the reduction of the forming voltage distribution is related to the volume of the conductive filaments that were formed in the nanodots. The fabrication of NiO nanodots and the detailed investigation of resistive switching characteristics that depend on the size of the nanodots provide valuable insights for future NiO nanodot resistive random access memory devices.