It definitely IS a tunnel diode. But not a semiconductor but a metal electrode one. The difference is, that the semiconductor tunnel diode of the 60ies shows a region of negative differential resistance which allows some interesting applications as oscillator nd so on. The MIM diode can not show this kind of behavior due to the different band structure of the electrodes.

My current understanding of the MIIM diode is, that its main application is as a demodulator/detecter for very high freqiencies.

A tunneling-based device may be ideally designed or optimized for high nonlinearity. But it should be recognized that tunneling is not expected to be a high current output mechanism matching CMOS. A MOSFET that is off is already a tunneling barrier (reverse bias pn junction depletion zone) with nonlinearity.

Yes quite true, the industries are desperately looking for the CMOS alternative that can work beyond Gigahertz, since this metal alternatives have got bandwidth ranging upto Terahertz, if this time the technology gets commercially accepted it will really open a new era.

Is this about CMOS or the material? I think we can still have CMOS design paradigm with another material beside Silicon. I hope we crack this code soon as it is long overdue. Something needs to help provide a new path for the continuation of Moore's law

Phononscattering "How is this supposed to "beat CMOS" or lead to transistors? My understanding so far is, that this is a two- not three terminal device. So it can not replace a transistor."

For a two terminal device structure, think of light or microwave input as the third terminal. Where the device is mounted in a lightwaveguide or a microwave guide. As we push frequencies higher those two will tend to merge. Quantum coupling efficiency will be the equivalent of gain.

The reliability of MIMs has been a problem in the past and limited widespread use. Given reliability they may find application in optical detectors in high speed backplanes. Who knows when TSVs run out of signal carrying capacity optical detection MIMs might allow TSV to be just holes!!

Ok, after some web searching I found comprehensive information. Seems like the technology itself is not new and has already performed well in the past, but failed commercially due to lack of differentiating applications.