Highly uniform resistive switching properties of NiFe2O4 films by embedding well-ordered pyramid-shaped Pt/Au nanostructures

Abstract

Switching instability significantly affects the development of resistive random access memories. An enhanced resistive switching uniformity was developed by embedding well-ordered Pt/Au nanostructures (NSs) in Pt/NiFe2O4/Pt devices. The well-ordered Pt/Au NSs arrays were developed on Pt/Ti/SiO2/Si substrates using 2D colloidal crystals as the deposition templates. The NiFe2O4 (NFO) thin films were then deposited on the Pt/Au NSs array via a spin coating technique, followed by annealing treatment. The memory devices were fabricated via Pt top electrode sputtering on the NFO film surface. The embedded device showed more uniform SET and RESET voltages and lower forming voltage than the non-embedded device. Distortion of electric field and temperature gradient around the Pt/Au NSs suppresses the random development of conductive filaments (CFs). Furthermore, the temperature gradient near the Au NSs could be relatively high during the forming process than in Pt NSs since Au has high thermal conductivity, promoting oxygen vacancy migration. Therefore, CFs easily nucleate in HRS and develop near Au NSs under the same bias voltage, leading to better resistive switching properties in the Au NSs array device than in the Pt NSs array device. This study provides an effective path for enhancing the resistive switching performances of devices.