Exploring the role of nitrogen incorporation in ZrO2 resistive switching film for enhancing the device performance

Abstract

The role of nitrogen doping on the resistive switching (RS) performance in nitrogen doped ZrO2 memristive device is investigated. The Pt/N:ZrO2/TiN resistive random access memory (RRAM) shows smaller switching voltage, larger memory window as well as improved uniformity. Moreover, the multilevel storage capability can be successfully obtained by varying the compliance current in the SET process for the memory cell. It is considered that the connection and rupture of conducting oxygen vacancy filaments (CF) can be localized and the oxygen ions (O2−) migration randomness is depressed due to nitrogen doping in ZrO2 film. Combining with the first-principle method, we theoretically calculate the formation energy (Evf), migration energy (Em) and density of states for oxygen vacancy (VO). Both Evf and Em values show noticeable decrease in N doped 2 × 2 × 2 ZrO2 supercell, which are related to the lower forming voltage and operating voltage. The density of states indicates that the oxygen vacancy midgap defect states can be eliminated as a result of N dopant, which neutralizes the excess defects in ZrO2 switching layer and may reduce the densities of the potential filaments. Herein the uniformity can be improved. All the theoretical results show reasonable agreement with the improved experimental RS performance for Pt/N:ZrO2/TiN device.