Resistive Switching in Nanogap Systems on SiO₂ Substrates

Voltage-controlled resistive switching in various gap systems on SiO2 substrates is reported. The nanoscale-sized gaps are made by several means using different materials including metals, semiconductors, and amorphous carbon. The switching site is further reduced in size by using multiwalled carbon nanotubes and single-walled carbon nanotubes. The switching in all the gap systems shares the same characteristics. This independence of switching on the material compositions of the electrodes, accompanied by observable damage to the SiO2 substrate at the gap region, bespeaks the intrinsic switching from post-breakdown SiO2. It calls for caution when studying resistive switching in nanosystems on oxide substrates, since oxide breakdown extrinsic to the nanosystem can mimic resistive switching. Meanwhile, the high ON/OFF ratio (approximately 10(5)), fast switching time (2 micros, tested limit), and durable cycles show promising memory properties. The observed intermediate states reveal the filamentary nature of the switching.