Other conduction mechanisms such as ions conduction (e.g., VCM-type memristor), metalic conduction (e.g., ECM-type memristor) may also involved in this structure.

Thank you so much. Can you provide me with related papers containing mathematical representation?

You can refers to "https://www.ece.ucsb.edu/~strukov/papers/2013/NatNano2013.pdf". This is a perfect review work on metal/oxide/metal junctions.

Thanks so much. I have not seen this paper before

Hello,

One of the unanswered questions in physics has to do with whether or not tunneling currents have anything to do with the functioning of the first commercially viable radio detector, the coherer.  While the coherer went out of fashion about 100 years ago, its direct lineal descendants include the MOM diode used for laser heterodyning and the STM (Scanning Tunneling Microscope).  It is thought that the metal-oxide-metal junction exists inside coherers, but how they function is still not known.  If you are interested, there is a thesis titled "Coherers, a review" on ResearchGate.

Regards,

Tom Cuff

I would suggest (as a starting point) study Simmons Model DOI; 10.1063/1.1702682