In-situ Experimente im Transmissionselektronenmikroskop zu den Mechanismen des resistiven Schaltens in Oxiden für nicht-flüchtige Datenspeicher
Final Report Abstract
These few, but the best of all available examples on observed microstructure changes related to forming and resistive switching demonstrate very clearly that this microstructure information is very fragmentary and not at all a confident basis for detailed microscopic mechanisms and models! This is especially true for the "filaments", which are "widely accepted as the resistive switching mechanism", mentioned in nearly every publication about resistive switching (especially of transition metal oxides) and very often described as a proven fact instead of an (assumed) model, because the complete sequence of forming and repeated switching has not been demonstrated yet for a "Filament" by microstructure changes in the bulk volume! In contrast, the reported observations are rather incomplete, sometimes inconsistent, and the interpretations and conclusions are quite often too strong and generalized. As an example, the observed sizes (diameter of areas) of the features claimed to be responsible for the switching are very scattered, even for very similar MIM systems, ranging from a few nanometers to several micrometers, and are sometimes contradictory, so that no reliable mechanism can be extracted from the observations at present! Instead, more open questions than answers result from the more detailed investigations leaving a wide field for additional, urgently needed research, if ReRAMs should make their way to application. It also shows that the work can be regarded only as the start for more of such experiments with the objective to shed light on the forming and resistive switching mechanisms by observation of microstructure changes, and in situ TEM technique seems to be the most direct way.
