Coexistence of Bipolar and Unipolar Resistive Switching Behavior in Ag/ZnMn₂O₄/p⁺-Si Device

Abstract

ZnMn₂O₄ thin films were deposited by a sol-gel technique onto a p⁺-Si substrate, and a RRAM device with the Ag/ZnMn₂O₄/p⁺-Si structure was fabricated. The microstructure of ZnMn₂O₄ films and the resistive switching behavior of Ag/ZnMn₂O₄/p⁺-Si device were investigated. ZnMn₂O₄ thin films had a spinel structure after annealing at 650 °C for 1 h. The Ag/ZnMn₂O₄/p⁺-Si device showed unipolar and/or bipolar resistive switching behavior, exhibiting different I _ON/I _OFF ratio and switching endurance properties. In bipolar resistive switching, high-resistance-state (HRS) conduction was dominated by the space-charge-limited conduction mechanism, whereas the filament conduction mechanism dictated the low resistance state (LRS). For unipolar resistive switching, HRS and LRS were controlled by the filament conduction mechanism. For bipolar resistive switching, the conduction process can be explained by the space-charge region of the p-n junction.

Keywords

ZnMn₂O₄ / resistive switching behavior / bipolar / unipolar