Uncovering the Indium Filament Formation and Dissolution in Transparent ITO/SiN_x/ITO Resistive Random Access Memory

The search for decent material systems is the most desirable to obtain superior performances in resistive random access memory (RRAM) devices. Nitride switching materials have attracted much attention in RRAMs due to their excellent device properties such as high-speed and low-energy switching. However, the unclear switching mechanisms, which have been characterized only indirectly, are a critical problem for continued RRAM optimization, especially in transparent devices with indium tin oxide (ITO) electrodes. Here, we demonstrate that transparent ITO/SiNx/ITO memories (∼82.4% transmittance in the visible region) can exhibit typically bipolar switching behavior. The indium filaments’ formation and annihilation were directly uncovered to be responsible for the resistance change via high-spatial-resolution transmission electron microscopy and energy-dispersive spectroscopy. Information on the dimensions and composition of the filament will provide a foundation to uncover the full switching mechanism in transparent nitride-based memories, offering great potential for RRAM design with high performances.