Controllable Formation of Nanofilaments in Resistive Memories via Tip-Enhanced Electric Fields

Resistive random access memory (ReRAM) has a great potential to be the next-generation non-volatile memory device. However, the random nucleation and growth of conductive filaments (CFs) in ReRAM causes the low reliability in switching behaviors, leading to difficulties in its practical application. This study demonstrates that manipulating electric fields in ReRAM via a structured electrode can provide the controllable formation of CFs. Ag pyramids that have a high-quality tip prepared via the template-stripping method generate highly enhanced electric fields at the tip. Because the tip-enhanced electric fields can facilitate the ionization of Ag atoms and their migration along the electric fields, the nucleation and growth of CFs occurs predominantly at the tip. The CFs in ReRAM are directly observed using electron microscopy and it is confirmed that the CFs are formed only at the tip. The resulting ReRAM exhibits low and reliable SET/RESET voltages (0.48 V ± 0.02 V and 0.15 V ± 0.06 V, respectively). Moreover, its endurance and retention time are highly improved, compared to those devices that are based on conventional geometry. Thus, this approach can encourage creating high-performance ReRAM.