  Resistance switching devices are of special importance because of their
application in resistive memories (RRAM) which are promising candidates for
replacing current nonvolatile memories and realize storage class memories.
These devices exhibit usually memristive properties with many discrete
resistance levels and implement artificial synapses. The last years,
researchers have demonstrated memristive chips as accelerators in computing,
following new in-memory and neuromorphic computational approaches. Many
different metal oxides have been used as resistance switching materials in MIM
or MIS structures. Understanding of the mechanism and the dynamics of
resistance switching is very critical for the modeling and use of memristors in
different applications. Here, we demonstrate the bipolar resistance switching
of silicon nitride thin films using heavily doped Si and Cu as bottom and
top-electrodes, respectively. Analysis of the current-voltage characteristics
reveal that under space-charge limited conditions and appropriate current
compliance setting, multi-level resistance operation can be achieved.
Furthermore, a flexible tuning protocol for multi-level resistance switching
was developed applying appropriate SET/RESET pulse sequences. Retention and
random telegraph noise measurements performed at different resistance levels.
The present results reveal the attractive properties of the examined devices.
