2D semiconductors anyone?

Subject: General Tech | July 19, 2016 - 12:37 PM |
Tagged: 2d, molybdenum sulphide, moores law, graphene

Over at Nanotechweb is an article on some rather impressive research being done to create what are, for all intents and purposes, almost two dimensional.  The process used by the researchers created transistors made up of two three-atom thick MoS2 layers, both slightly overlapped with graphene, sandwiched between two one-atom think graphene layers.  The trick is in the use of graphene, itself unsuitable for use as a transistor but perfect for interconnects thanks to its conductance.  Read on to learn more about these researchers and the process they are working on, including a link to their publication in Nature.


"Researchers in the US have succeeded in chemically assembling the electronic junctions between a 2D semiconductor (molybdenum sulphide) and graphene, and have made an atomic transistor with good properties. They have also assembled the heterostructures into 2D logic circuits, such as an NMOS inverter with a voltage gain as high as 70."

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Source: Nanotechweb

Graphene coated copper shows significant promise

Subject: General Tech | June 19, 2015 - 01:00 PM |
Tagged: graphene, copper, interconnect

Earlier this week we heard news about IBM's research into optical transceiver chips and today comes news at The Register of another interesting project to increase the frequency of processors by sheathing current copper interconnects in graphene.  This is not the first time the usage of graphene has been investigated for computers, indeed there is research being conducted into improving non-volatile storage and even cooling with the use of graphene. The project being carried out by a team at Stanford University found graphene-coated interconnects can reliably carry data at speeds 4-17% faster than copper without the sheathing.  They feel that a 30% improvement is reachable with current process technology; you can read more in the full article.


"Researchers have made tremendous advances on all of the other components in chips but recently, there hasn't been much progress on improving the performance of the wires," said Stanford electrical engineer Philip Wong."

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Source: The Register

Is there a Flash flood coming?

Subject: General Tech | March 25, 2013 - 12:50 PM |
Tagged: spintronics, racetrack, pram, molybdenum, micron, memristor, IBM, hp, graphene, flash

Over the past several years we have seen actual production of phase change memory from Micron, though no benchmarks yet, transistors whose resistance can be altered to be used as non-volatile storage which HP has dubbed Memristors and IBM's Spintronic Racetrack Memory; all of which claim to be the replacement for NAND.  There is no question we need a new type of flash, preferably non-volatile, as it is likely that there will be a limit on effective speed and density reached with traditional NAND.  It is also true that the path to our current flash technology is littered with the carcasses of failed technology standards, whether RAMBUS is willing to admit it or not. 

Now there is more details available on yet another possible contender based on molybdenum disulfide which sports a charge-trapping layer to make it non-volatile.  The Register was told that by layering MoS2 between layers of graphene they get a NAND cell smaller than traditional cells but unfortunately there was no report of the speed of these cells.  We may soon be living in interesting times, with process shrunk traditional flash and these four technologies competing for market share.  You can bet that they will not be compatible and that each will likely spawn their own breeds of controllers and make purchasing SSDs and other flash storage devices much more complicated, at least until one standard can claim victory over the others.


"A Swiss government research lab has reinvented flash memory using graphene and molybdenite in a way that should be faster, scale smaller, use less energy and yet more flexible than boring old NAND.

Molybdenite is MoS2, molybdenum disulfide, which is similar to graphite and also has a lubricating effect. Atomically it is a layer of molybdenum atoms between top and bottom layers of sulfide atoms. It is a semiconductor and can be used to create transistor."

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Source: The Register

Nanotubes will make fast non-volitile memory even if they are slow out of the gate

Subject: General Tech | November 7, 2012 - 03:29 PM |
Tagged: graphene, nanotubes, NRAM, non-volitle RAM, Van der Waals, Nantero

Nantero promised us that their nanotube based flash memory would be available in 2009 and disappointed us by failing to reach that goal but The Register has some great news, they currently have 4Mbit arrays of NRAM up and running in their labs.  These arrays are writing data as fast as 3 nanoseconds while producing reasonable heat and consuming what is described as low power.  Perhaps even more important in a market which is currently quite worried about the lifetime of flash memory, this nanotube based RAM has no write limit whatsoever and if it makes it into SSDs it will assuage the fears many users currently have.  The memory works based on resistance, when the tubes are not touching they are in a state of high resistance which represents a 0 and when touching they have low resistance and represent a 1.  The stiffness of the nanotubes keeps them in a separated state until close enough that the Van der Waals force keeps them touching ensures that this will be non-volatile RAM and will retain data without an external power source.  Hopefully we will be seeing more on this soon.


"Carbon nanotubes (CNTs) are cylindrical carbon allotropes, molecules up to a millimetre long but just a nanometer thick, and have a length-to-diameter of up to 132,000,000:1. Their walls are made up of single-atom-thick carbon sheets - graphene. CNTs are members of the fullerene family and their properties include the ability to conduct electricity as well as copper, while being stronger than steel and as hard as diamond."

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Source: The Register

Composite Copper and Graphene to make a cool couple.

Subject: General Tech, Cases and Cooling | April 10, 2012 - 06:03 PM |
Tagged: graphene, cooling

Researchers at NC State University have tested the heat dissipation properties of copper-graphene. Their findings suggest that the material could be cheaper and more effective than pure copper.

Some people have gone to ridiculous lengths to cool their components. Some people flush their coolant regularly. Some people will never live down mineral oil jokes. No two computers are not on fire. Awwww.

Copper is regularly used as a method of dissipating heat as it is highly efficient when sufficiently pure. While copper is expensive, it is not expensive enough to be prohibitive for current use. Alternatives are still being explored and a researcher at NC State University believes graphene might be part of the answer.


Some people stick a bathroom suction fan out a window and run a 3” drier hose into their case.

As always, I become immediately skeptical when a team of researchers make a claim such as this. Whether or not these issues are valid have yet to be seen, but they come to mind none-the-less. The paper claims that the usage is designed for power amplifiers and laser diodes.

My first concern is with geometry. Effective cooling is achieved by exposing as much surface area between two materials as is possible for the situation. Higher heat conductance allows heat to get away much more efficiently, but the heat still needs to be removed to a reservoir of some sort, such as your room. There has not been much talk about the possibilities to then remove the heat after copper-graphene so efficiently sucks from the heat source.

My second concern is with the second layer of indium-graphene. While it seems as though the amount of indium required is quite small -- just a single layer between the heat source and the copper-graphene -- we do not really know for certain how that relates to real world applications. Indium is still a very rare element which is heavily mined for touch screen devices. It might prove to be cheap, but there is only so much of it. Would we also be able to reclaim the Indium later, or will it end up in a landfill?

These concerns are probably quite minor but it is generally good practice to not get too excited when you see a research paper. Two points if you see any of the following: Nano, Graphene or Carbon Nanotubes, Lasers, and anything related to High-Frequency.