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.
Silver too expensive?Not really, when you get down to sub 20nm lithographic dimensions it is more about number of atoms used than the number of ingots. The possible problems with silver are more technical than they are fiscal. Although from a fabrication point of view not much more difficult than introducing copper, now routine.
Those who wish to pursue this silver based memory must first have a firm belief than NAND/NOR will not be able to evolve enough to do the job required of it in the future. The private sector does then give them the opportunity to help underwrite a possible winner. In analogy, the secret of success for those who wish to invest time and/or effort is to separate the signal from the noise.
Against all the potential problems that must be solved the Crossbar memory does appear to offer what I would call a win-win-win situation as an integral part of the memory cell in that it provides: uni-directional matrix isolation, allows the bidirectional current flow required for memory operation and reduces fabrication processing steps.
As somebody who in the past has looked at long carrier lifetime diodes to obtain reverse pulse current flow as well as punch through diodes for matrix isolation to me the Crossbar memory looks worth a development opportunity.
I think this is still a CBRAM, similar to the one used by Adesto. It relies on diffusing Ag. However, Adesto uses a chalcogenide rather than amorphous silicon. Amorphous silicon is highly temperature sensitive as it is still semiconducting silicon.
Having seen all too many claims about NAND/DRAM replacements over the past 20 years that will be ready for commercialization either next year or the next 2 years or the next 3 years, I have to express amazement that people still get tens of millions of dollars for this. Stan Ovshinsky was the ultimate expert at getting all sorts of companies from Intel to Exxon to give him literally hundreds of millions of dollars over decades for multiple wild projects, very few of which ever resulted any products and even fewer resulted in earnings of any sort. I think ENER might have been that last one and they too went bankrupt.
When someone talks about the magic of the private sector, I either laugh or grimace, depending on my mood at the time.