Filament formation and erasure in molybdenum oxide during resistive switching cycles

Abstract

In-situ filament observations were carried out on the Cu/MoOx/TiN resistive random access memory (ReRAM) by using transmission electron microscopy. Multiple positive and negative I-V cycles were investigated. Clear set-reset bipolar switch corresponding to the characteristics of conventional ReRAM devices was recognized. Filament grew from TiN to Cu in the set cycle and shrank from TiN to Cu in the reset cycle. However, there was no clear contrast change in the image at the switching moment, and thus, switching is thought to occur in a local region of the filament. When the current was large at reset, the filament shrank much, and its position tended to change.

Microstructural transitions in resistive random access memory composed of molybdenum oxide with copper during switching cycles

“…There was also a region with dark contrast near the MoO x /ox-TiN/TiN interface, which may correspond to the region of a Cu deposit, as reported earlier. 47,53 This was also observed in the initial state.…”

“…This is caused by the thin ox-TiN layer that is formed on the TiN BE, as discussed in our previous work. 53 The…”

“…A detailed discussion of this second switching cycle has already been undertaken in our previous report. 53 In this report, therefore, only a brief explanation will be given for comparison with the other switching cycles. Starting from state b, the set switching occurred at around +2.3 V (states c and d).…”

“…In addition to perovskite-type ReRAMs [37][38][39] and devices based on binary oxides, [40][41][42][43][44][45][46] many reports on CBRAMs have appeared in recent years. [47][48][49][50][51][52][53] In one example, the dynamic growth and rupture of a Cu CF was confirmed during a switching cycle. 47,51 In another report, the CF growth scheme was investigated in detail in terms of its dependence on cation mobility.…”

Reversible voltage dependent transition of abnormal and normal bipolar resistive switching

“…Based on the RS region, RS can be categorized into two types, bulk type with conducting filaments and interface type with tunneling barrier height and width modulation791011. The reversible structure modification and resulted RS mainly originates from the thermal activated7 or electric field driven ion migration, such oxygen vacancies1213, metallic electrode atoms14, etc. The RS is also very sensitive to the selected electrode, and abnormal BRS might be observed with fixed resistance state at zero field no matter the RS at high field1516.…”