Lithography-Free Miniaturization of Resistive Nonvolatile Memory Devices to the 100 nm Scale by Glancing Angle...

The scaling of nonvolatile memory (NVM) devices based on resistive filament switching to below a 100 nm² footprint area without employing cumbersome lithography is demonstrated. Nanocolumns of the organic semiconductor 4,4-bis[N-(1-naphthyl)-N-phenyl-amino]diphenyl (α-NPD) were grown by glancing angle deposition on a silver electrode. Individual NVM devices were electrically characterized by conductive atomic force microscopy with the tip of a conductive cantilever serving as second electrode. The resistive switching mechanism is unambiguously attributed to Ag filament formation between the electrodes. This sets the upper limit for the filament diameter to well below 100 nm. Full functionality of these NVM nanodevices is evidenced, revealing a potential memory density of >1 GB/cm² in appropriate architectures.