The resistence-switching mechanism within Crossbar's memory is based on the formation of a filament by the movement of silver ions from the top electrode within amorphous silicon. Source: Crossbar Inc.
Yjdong:-Looking at other metals and Shottky formation, I suppose the question is how much is the original amorphous silicon structure disturbed by the movement of metal into and out of that structure, the ideal situation would be not at all. My view is that would only occur if the movement was electro-migration/current density/diffusion driven, candidates Ag, Cu and even Gold.
In which case the metal poly/single crystal contact would most likely be considered a Shottky. I would suggest that trying to detect how much the amorphous structure has changed would be the basis of the analytical technique.
As one moves away from that ideal situation the alloying of the metal with the amorphous silicon has to be considered. In the extreme case that would be say a VIA formed using a refractory metal and a-Si where say an irreversible W-Si alloy link is formed. In the intermediate case if in its molten state the Si-X alloy can form an electrochemical cell that would provide the needed reversibility for an NV memory. In all three cases the threshold switching effect displayed by a-SI provides the means for localizing the current and raising the temperature.
So it all boils down to the key question: how does this Ag-aSi system conduct vs. temperature? Is there a Schottky fit? Is there an activation energy? Could there be a crystallization temperature involved?