Effect of top electrode material on resistive switching properties of WN based thin films for non volatile memory application

The influence of top electrode (TE) material on resistive switching properties of DC magnetron sputtered tungsten nitride (WN) thin film with TE (Ti, Al and Cu)/WN/Pt stack configuration has been investigated. Bipolar resistive switching behavior has been clearly found for all the three top electrodes. The memory cells with Ti and Al top electrodes exhibit two resistance states i.e. low resistance state (LRS) and high resistance state (HRS) switching which is caused by formation and rupture of ionic filaments. The formation of additional Cu filaments in WN layer are responsible for three resistance states (or say multilevel) switching for Cu top electrode. Temperature vs resistance measurement confirms the formation of ionic and metallic filaments. The WN thin film based ReRAMs show an excellent endurance over 10⁵ cycles and non volatile long retention of 10⁵ s along with ∼10² resistance ratio between HRS/LRS. This study suggests that the electrode engineering of WN based ReRAM devices have potential in nonvolatile and multilevel resistive switching memory. - Highlights: • (Ti, Al & Cu)/WN/Pt were fabricated and investigated the resistive switching. • Multilevel (three level) switching has been achieved with Cu top electrode. • Switching capability has been explained by the conductive filamentary model. • (Ti, Al & Cu)/WN/Pt devices show excellent endurance (10⁵) and retention (10⁵ s).