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nonvolatile
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Re: "CBRAM"
nonvolatile   8/7/2013 12:26:04 PM
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By the way Peter, Not that I am in the Silver CBRAM boat, but I just want to remind a few that Ag is a transition metal too---

nonvolatile
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Re: localized conduction?
nonvolatile   8/7/2013 12:20:35 PM
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Sorry CEO - this is not joule heat. It is also not "localized", but can be made as big as a 44 by 44 micron device, and still turns on at nearly zero volt. It would be really hard to fire up something like that with a pulse generator, don't you think?

Try something less "classic". Try electron localization (not of the Anderson type, found in heavy doped MOSFETS);

An electron just a few angstron from the core ion gets localized if the electron density (from 4s states and injected)  goes down to a critical level following { a }*cubic root of n) = 0.26., where a is the bohr radius and n is the critical electron density----time to dust off that old copy of KITTEL my friend.

Not every material should be understood with a simple shortenned hamiltonian - try to add wannier functions or a tight binding model plus a coulombic localized interaction....

nonvolatile
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Re: "CBRAM"
nonvolatile   8/7/2013 12:10:34 PM
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Yes, I remember your name, but did not recognize your picture - that was 27 years ago. We are sure crazy still doing this stuff. Thanks for the remembrance. I did not want to review our company at first because we are sending papers to Nature etc, then we would enter in conversations with licensees. The IV characteristics and other parameters of this device are explained with things like "lesser Greens's Functions" and other concepts not so common in the semicoductor industry, so I wanted to place this into the top journals. Thus, 2 years ago we published 3 papers in the journal of Applied physics. These wer verysuperficial but strong enough to get some interest going, Then I went to the last IEDM, where I was recognized as a new IEEE fellow, and I was very upset to see that nothing had changed in this filament world. Classic reviews like Imada's in Phys rev. clearly cast the "new Electronics" in the world of TMOs. Imagine a 2 terminal switch without silicon in Femtosecond speeds, So, I could not resist.

resistion
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Re: localized conduction?
resistion   8/7/2013 11:56:07 AM
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So you have area independent conduction? It's localized then? Though not exactly like RRAM filament, maybe it still has similar effect like self-heating?

Peter Clarke
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Re: "CBRAM"
Peter Clarke   8/7/2013 11:55:25 AM
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Hi Carlos

You may not recall, but I remember talking to you shortly after the formation Symetrix Corp. when I was working on Electronics Times.

nonvolatile
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CEO
Re: "CBRAM"
nonvolatile   8/7/2013 11:49:31 AM
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Dear Peter/Staff,

I would like to first answer the question on Temperature dependence of the Mott transition.

Yes, in VOx that is the case - but the true definition of a Mott transition is quite complex and is still an area of major study in condensed matter physics. That being said, it is better to consider this without the specific lable "Mott Transition" to the more general label of "Metal Insulator Transition (MIT)" and the reverse IMT. Now, the well known formula of the relationship between electron density and lattice length -a - is 1/n = (4/3)(pi)r^3, in this sense (in a very rough manner), we can see that r is the radius of the ion-core potential. So, as you can see, if r=bohr radius we have no bound state and the material is a metal. If r=screening length which is related to 1/n and the density of states, a reduction of electron density is just enough for the screening length capture an electron and form a bound state. Subsequent to that, we then have electrode polarization that injects electrons in the cathode side at Vset, and when at a lower voltage it starts the on mode (metal side), it injects holes and attract electrons in the anode side . As the quantum phase transition is of the order of femtoseconds, we have the ability to shut off electron flow because  (1) the barrier for electrons in the cathode is high now, as Vapplied is smaller, and (2) The electron deficit near the electrodes trigger the bound state to be create faster than the drift velocity of the electrons that may still jump the cathode barrier. This lack of thermal equilibrium is the reason why the insulating state now comes into play and the device is off. Stability of Vset and Vreset, together with Low on current are key for device reliability, Also, it is necessary to really model this device using the tools of many body physics, where the electron-electron interaction is dominant. Such electron localization is not used in semiconductors and common materials because the bloch electron does not interact with other electrons when it is in the conduction band. So, textbooks in semiconductors and simplistic filament or not brute force devices will never be reliable, as we have a physical phenomena embedded in a sea of defects. To summarize, This is a complex device - it is controlled by a baseline MIM diode with a quantum phase transition that is electron density driven. Without concepts from many body theory, such as Self-energy etc. it is a real pain to explain the phenomenon and "sell" the idea.So Data talks and the rest walks - and for this reason we kept quite.

My company has its own financial resources and it is privately owned. Now, we may have to open for capital infusion but we may not have to.

We do not follow the capital raising path and we are 27 years old with a portfolio of over 200 patents. We sold many licenses, and the royalty stream is enough to continue innovation. We are responsible to about 1.3 Billion devices in the market in many areas. Eliminating the influences of chasing money, we believe that true innovation must be fundamental and game changers. So, we took good care of this discovery and we are working in materials beside NiO already for magnetic oxides and light switches, This is truly a magnificant chance to innovate electronic devices - there is no nonvolatile memory without some form of hysteresis. Even flash has a threshold voltage hysteresis due to floating gate charge trap and reflection of that to the channel. So, since all electrodes from 65 nm down are nickel silicide, the low temperature NiO is key, and the elimination of Pt as an electrode is just right, Imagine, we have NiO with Al electrodes, talk about a post process memory for the embedded guys. So we have designed a 64M device for the 22 nm node and we are doing TEGs to get full design parameters etc.

We are the guys that many years ago made front page with nonfaigue FeRAM. By using SBT instead of PZT, we have the world's most used FeRAMs coming out of Panasonic. Yes, it had an embedded microcontroller in every SUICA and it is in playstations, drivers licences and a myriad of devices. It works at 1.1 Volts in the 0.18 micron node and can be made as this as 25 nm for future nodes. Unfortunately, since 65 nm and below, annealling cannot go over 400 C, ferro is not going to large scale. So, we quietly switched to do ReRAM, but came out as CeRAM, so that we work in the realistic world based on solid physics.

My Company is Symetrix Corporation - Colorado Springs.

I recieved in 2006 the IEEE Daniel Noble award for FeRAMs and I am an IEEE fellow, so now you can discount exuberant enthusiasm as found in many memory house start ups.

CArlos A. Paz de Araujo

 

nonvolatile
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CEO
Re: "CBRAM" Interesting
nonvolatile   8/7/2013 11:07:22 AM
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Manager 

You are correct, but such a preliminary analysis you should understand that we have already done. This was 6 years ago.

The key issue is that area dependence is almost zero in the conductive sice, but the non-conductive side, is really an MIM diode-like device. Such a device would have area dependence whether you have filaments or not. This area dependence of the high resistive side is beneficial because in fact it enhances the read noise margin. The problem is that in filamentary devices, the random connect/disconnect does not afford   good and systematic stability of what the diode induced area dependence is. Think of it as a "soft broken " insulator.

Now, your suggestion about a thermal effect creating filaments and we just missed them has been deeply studed, specially in the case that the active region is in the metal and of only 5-20 nm. The doped NiO of the outside buffer layers are always conducting as the pi bond of the CO:Ni is a strong electron donor. So, there is a direct short from electrode to the active region. Within that region the Ions have just enough electrons to switch on or off the coulombic interaction U. So, there is no possibility that a large highly conductive region connecting the electrode to the active region to form filaments. And, a thermal filament formation would show variations as the 20 nm layer would be stuck in an always on connected filament. Very high Resolution TEM and EELS show the right mechanism, but if you missed the point of the doping and the octahedral crystal field control of the oxidation number, I can see that it is easy to look for other explanations.

Perhaps you could take a look at a wikipedia article on Mott Insulators and see that an enormous effort in the last 60+ years, found Metal to Insulator transitions in TMO without ever mentioning filaments.

Finally, let me add that one of the most difficult problems with ReRAMs is the high on current - filaments in the majority of the case are metallic and follow the patch surrounding grain boundaries - so, how to lower the on current. In our case, the CO doping and element doping are independent mechanisms, so we can dope for coordination correction with CO and for scattering increase to lower the on current 5 orders of magnitude. If we had filaments, such a control of the on current would be impossible.

Peter Clarke
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Re: "CBRAM"
Peter Clarke   8/7/2013 11:01:25 AM
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Interesting claims that seem to be based on the Mott transition in such materials as nickel oxide and vanadium oxide.

We do wish you will tell us more about what you have done, for what company and how you have been funded.

Is it not the case that there is a temperature associated with Mott transitions which can be in the room temperature range? Is it necessary to somehow remove that temperature dependence to avoid reseting of memory?

 

 

 

 

resistion
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Re: "CBRAM" Interesting
resistion   8/7/2013 10:41:42 AM
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I am intrigued. To prove your memory is non-filamentary, it must show resistance that has weaker than inverse proportion to area dependence. In addition, although not commonly shown, the burden of electroforming may be significantly relieved thermally. I.e. the formation of defect-based RRAM may proceed with a similar process to CeRAM. For different reasons, of course.

nonvolatile
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CEO
Re: "CBRAM" Interesting
nonvolatile   8/7/2013 10:17:36 AM
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Correction: 3d8 splits into "3d7 and 3d9". Sorry for the typos.

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