[HN Gopher] Researchers claim first functioning graphene-based chip
___________________________________________________________________
Researchers claim first functioning graphene-based chip
Author : Brajeshwar
Score : 344 points
Date : 2024-01-19 14:52 UTC (1 days ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| causal wrote:
| If I'm reading this correctly, this would more accurately be a
| graphene wafer, right? There are no circuits on this thing, it's
| just a sheet of graphene, right? Still remarkable if so, just not
| what I would call a "functioning chip".
| OnACoffeeBreak wrote:
| I only scanned the article and the paper, but the paper linked
| in the article talks about the researchers characterizing
| performance of a MosFET.
| gwill wrote:
| yea, looks like the author doesn't understand the difference
| between a semiconductor and a chip.
|
| the researchers said "functioning semiconductor".
| deepsquirrelnet wrote:
| Likely single devices patterned from a epitaxially grown
| graphene layer. It would be a functioning transistor --- or set
| of transistors, albeit not terribly useful as single devices.
| Typically they would pattern the devices with large metal
| landing pads to drop probes onto, and perform characterization
| from there.
| idiotsecant wrote:
| The difference is just engineering once the material science is
| there.
| kaptainscarlet wrote:
| This could be the breakthrough that could miniaturized AI more
| powerful.
| programjames wrote:
| This is still years away from mass production. The process
| takes hours at very high temperatures to make a single layer.
| givinguflac wrote:
| Nope, it takes about an hour for one layer.
|
| FTA: "Then a high-frequency current is run through a copper
| coil around the quartz tube, which heats the graphite
| crucible through induction. The process takes about an hour."
| programjames wrote:
| My mistake, I read the paper days before I wrote my
| comment.
| dylan604 wrote:
| Having a title for anything with "Researchers claim..." is such a
| red flag that I don't even want to click the link. I've been
| burned too many times. I know that fire is hot, I don't need to
| touch it again to find out. I'm a quick study, and after the 10th
| time, it took hold
| colordrops wrote:
| Speaking of graphene, I've been hearing about its miraculous
| powers for years. Are there any practical applications yet?
| theragra wrote:
| It is used in industrial uses widely, for composites with
| greater durability, strength etc
| theragra wrote:
| Also, for fun, search for nano tape. I think it is using
| carbon nano structures, close relatives of graphene
| dotnet00 wrote:
| I'm not sure if they're available on market already, but I
| recall that graphene Li-ion batteries are being seen as a
| decent near term upgrade, with the production issues of
| graphene reduced because they don't need large sheets of it.
| bogtog wrote:
| Isn't it notable that the article is at least acknowledging
| this uncertainty?
| bee_rider wrote:
| The manufacturing process seems quite friendly compared to the
| (albeit, local) ecological nightmare that is Si.
|
| It sure is hard to compete with half a century of Si advancement,
| though. Especially given how many STEM-brains get attracted to
| software instead, nowadays...
| varispeed wrote:
| > Especially given how many STEM-brains get attracted to
| software instead, nowadays...
|
| It's just common sense. You won't earn decent money at
| semiconductor company and given the niche, you will be
| sentenced to whims of one or two (if you are lucky) companies
| operating in your region. If you find that your employer
| doesn't treat you well, you cannot exactly leave and bootstrap
| your own chip making business.
|
| Software is more democratised and you have much better chances
| to grow wealth of your family in that area. Although corrupt
| regulators are doing their best to pull as many ladders as they
| can to limit ways workers can go their own way (like changed
| IR35 legislation in the UK that massively limits how small
| service based business can operate).
| bee_rider wrote:
| I agree that the market has shifted in a way that we're all
| individually making the rational decision by going into
| software, but it still seems like a shame.
| mindentropy wrote:
| It is simple. If the Govt wants to support the semiconductor
| industry provide proper worker protections. It should know
| that the a few companies would have cartel like power and
| exploit their employees.
| idiotsecant wrote:
| Its rare that nuanced problems have simple solutions. The
| problem is not that evil employers are oppressing helpless
| employees, at least not entirely. The problem is that
| making physical things requires physical infrastructure and
| investment at a massive scale. Things move slowly and
| barrier to entry is high. Conditions like that are going to
| cause a slower, less transferrable skill set just because
| few entities are willing to take the capital risk to
| develop that infrustructure so fewer entities exist.
|
| Contrast that with software where you and I could go start
| a business _now_ and potentially unseat a major player
| somewhere with enough talent and dedication.
|
| Its obvious which one is going to have more mobile
| employees.
| robertlagrant wrote:
| It's not worker protections that will help. They will just
| end up incentivising industry to move elsewhere. The
| problem is it's too hard to set up competitors. Competitors
| are what raise employees' standards of living, far higher
| than vote-winning legislation.
| ngneer wrote:
| This is right. The flip side is that having many talented
| software engineers renders each one slightly more
| dispensable. You want to find the right Goldilocks niche. Not
| too rare that mobility is limited, but not too prevalent that
| compensation suffers.
| tyre wrote:
| As a hiring manager, I can confidently say that we are
| nowhere close to saturated with talented software
| engineers.
| agumonkey wrote:
| so the niche is in training ? :D
| throwaway22048 wrote:
| Yes, I earn 3x more doing training than myself or any of
| my senior SWE colleagues/friends. Think 1500 EUR daily
| rate instead of 500 (in Central Europe).
| bboygravity wrote:
| * talented very experienced software engineers under 35,
| who are willing to work on-site full-time (which often
| means move to the company) and are allowed to work in the
| US?
|
| Or am I being too synical?
| Firmwarrior wrote:
| Software is the easiest thing in the world to outsource.
| There's no reason we can't play Chinese-made games or use
| Indian-made chat apps
|
| Market forces (more demand than supply) are what push
| coding salaries into the stratosphere
| burnished wrote:
| Yep! When I was in school and learning about semiconductors I
| was so interested that I went to the library for further
| reading and dropped by the physics department to ask
| questions, purely for my own edification. But I chose to
| pivot towards software due to the career prospects.
| soitgoes511 wrote:
| Won't earn decent money? Have you ever worked for a big semi
| company? I have and that is simply not true. Niche, maybe...
| But, they did not skimp high performers regarding wage.
| Believe it or not, there are plenty of good software
| positions in semiconductors too..
| rbanffy wrote:
| > you will be sentenced to whims of one or two (if you are
| lucky) companies operating in your region.
|
| Or you work at a foundry-less IP house. There are many of
| those.
| crotchfire wrote:
| Just wait until they scale it up and commercialize it; the
| nightmare will return.
|
| The sad fact is that nasty and exotic chemicals provide ways to
| make many manufacturing processes cheaper and run large
| batches. When you're pushing the limits of _everything_ and the
| stakes are high, you can 't really take them off the table.
| programjames wrote:
| Where did they claim to make a chip? It seems to be just a single
| epigraphene layer.
| jacquesm wrote:
| 'just'?
| robertlagrant wrote:
| A chip is a lot harder than a wafer, and a chip is what's
| claimed.
| jacquesm wrote:
| From nothing at all to a wafer of a new material is a giant
| step compared to the step from a wafer to a chip.
| topspin wrote:
| Is it? What is the plan for depositing these materials
| with precision to implement logic? Doesn't seem like
| conventional lithography is applicable.
| h0l0cube wrote:
| According to a sibling comment they already made a FET
|
| https://news.ycombinator.com/item?id=39057303
| topspin wrote:
| That paper describes using e-beam deposition: they're
| using an electron beam to fabricate individual components
| in the lab.
|
| That's fine for experiments. It has zero value for making
| devices with billions of components. Unless there is
| something akin to lithograph techniques you can't make
| products economically.
| jacquesm wrote:
| It would seem a bit much to require that they jump from
| 'have a wafer' to 'volume production' overnight. But the
| fact that they can use electron beam deposition to
| fabricate indicates one very important thing (to me, at
| least): the same kind of technologies that can work on
| Silicon wafers appear to be viable for these Graphene
| based ones. And that would allow recycling a whole pile
| of tech, possibly speedrunning through the last bunch of
| feature sizes because of all of the experience gained
| with Silicon. To me it says Graphene will now work in the
| next five to ten years _or_ it will likely never happen.
| It would need to outperform Silicon on at least one
| metric (density, power consumption, speed) to make it
| worth it for niche applications and then bit by bit
| economies of scale would take over.
| programjames wrote:
| To be fair, epigraphene wafers already existed, they just
| weren't nearly as pure.
| photochemsyn wrote:
| Full research article:
|
| https://arxiv.org/pdf/2308.12446
|
| They did make a proof-of-concept device: "The electrical
| properties of the SEG were measured by characterizing a
| fabricated top-gated SEG FET."
| ngneer wrote:
| Trouble is always with scaling and equipment. Unless one uses the
| existing infrastructure, low chance of success.
| px43 wrote:
| I also think that a fundamental issue with using carbon for
| compute is that we don't actually have a lot of it, and what we
| do have we largely need for all that organic chemistry that
| keeps us alive.
|
| For reference, carbon makes up about 0.18% of the earth's mass,
| whereas silicon makes up 27.7%. The moon basically has zero
| carbon, and the regolith is 20% silicon.
| AdamH12113 wrote:
| Far more of the silicon (from sand) goes into concrete and
| glass, though. And it's not like we're short on hydrocarbons.
| From what I can gather, the total yearly worldwide production
| of concrete is tens of billions of metric tons, fossil fuels
| are billions of tons, and silicon is millions of tons --
| barely a blip on the radar.
| h0l0cube wrote:
| And imagine running out of coal!
| klysm wrote:
| It's not like we're anywhere close to short on Si though...
| not sure it's a relevant comparison
| mthcalixto wrote:
| Graphene is the future and Brazil is the largest country that has
| this resource, it could be the best country in the world.
| dtx1 wrote:
| Isn't graphene just carbon?
| ur-whale wrote:
| I thought Graphene was just a form of Carbon, and mostly
| produced from regular carbon through some sort of process.
|
| Are you saying Graphene can be found in nature?
| binarymax wrote:
| Graphene (https://en.m.wikipedia.org/wiki/Graphene) is
| manufactured from carbon. You don't pull graphene out of the
| ground, you manufacture it in a lab.
| neuronexmachina wrote:
| I've been playing too much Dyson Sphere Program lately, my
| first thought was "you just need to combine graphite and
| sulfuric acid in your chemical plant": https://dyson-sphere-
| program.fandom.com/wiki/Graphene
|
| Looks like that's sort-of a real thing?
| https://www.americanscientist.org/article/mass-producing-
| gra...
|
| > Researchers at Rutgers University are making sheets of
| graphene out of ordinary graphite flakes and some sulfuric or
| nitric acid.
| seaal wrote:
| Always nice when games introduce you to real life concepts.
| Shout out to Greg Tech: New Horizons, often leading me down
| a wikipedia rabbit hole.
| klyrs wrote:
| Even if you could just magically make a reel of graphene
| with this graphite+sulphuric acid recipe, it wouldn't help
| one bit in chip fabrication. You need to build things layer
| by layer; there's only one place where a bulk material is
| used, and that's the substrate.
| r3d0c wrote:
| lol.. unless brazil is the only country in the world with
| carbon, this is absolutely not true
| neuronexmachina wrote:
| Assuming you mean graphite (which can be used in graphene
| production), it looks like Turkey might have even more
| reserves. China, Madagascar, and Mozambique also have pretty
| significant graphite reserves:
| https://www.statista.com/statistics/267367/reserves-of-graph...
| wigster wrote:
| its made out of sellotape/scotch tape and pencils! ;-)
| cassiogo wrote:
| I belive you are thinking about Niobium and not Graphene
| dudeinjapan wrote:
| Brazil is the world's third largest producer of graphite,
| behind China and Mozambique. Our current most reliable graphene
| production methods start with graphite and exfoliate it into
| single layers of graphene.
| moffkalast wrote:
| Even if that were true, countries where most of the wealth is
| dug or pumped from the ground are the worst places to live
| because it can all be be easily extracted by foreign companies
| who pay a cut to the dictator directly and the people have
| nothing to threaten the laughably rich autocrat with.
| margorczynski wrote:
| The question is can this be as effectively processed and
| miniaturized as silicon. Still as someone pointed out they've
| already produced a transistor based on it and the claim is the
| same processes used for silicon can be used here so I sure hope
| it works out.
| mcshicks wrote:
| Silicon based chips rely on oxide and metal layers to connect
| the transistors. Not clear to me from the article how that
| would work for graphene based devices. This was also an issue
| for GaAs based chips. From the Wikipedia article on GaAs
|
| "The second major advantage of Si is the existence of a native
| oxide (silicon dioxide, SiO2), which is used as an insulator"
| anticensor wrote:
| Carbon conductors to connect between layers, and carbon
| dielectric as insulators. Carbon all the way.
| EasyMark wrote:
| Yep, we have much faster switching semiconductors than silicon
| based ones, but that is like 10% of the deal; there is also
| miniaturization techniques, fab equipment, engineer/scientist
| expertise in the subject, conductor/semiconductor/insulator
| layers & interfaces, and oh so much more. It's nice to hear
| about advancements outside the regular silicon ecosystem but
| it's a tough row to hoe to push silicon aside for a "better
| material". It's probably going to have to be a revolutionary
| advantage (100x?) improvement over current tech to move to a
| new tech stack.
| dotnet00 wrote:
| Since density with Si is approaching a wall soon and thus a
| switch in materials likely to end up being necessary at some
| point in the next 2-3 decades anyway, I feel like rather than
| being immediately revolutionary, all that'll end up mattering
| is where the theoretical limits are. After all, at that
| point, you need to retool and retrain anyway.
| moffkalast wrote:
| Even if it can't, ridiculously high current mosfets without
| heatsinks FTW.
| throwbadubadu wrote:
| > The outcome is transistors capable of operating at terahertz
| frequencies, offering speeds 10 times as fast as that of the
| silicon-based transistors used in current chips.
|
| Why? We are single digit gigahertz, so terahertzes should be ~
| 100 times faster?
| daveFNbuck wrote:
| We're at single digit gigahertz for an entire chip, not a
| single transistor.
| AdamH12113 wrote:
| The clock frequency is single-digit gigahertz. But digital
| signals have to propagate through multiple layers of logic
| gates, so the transistors have to switch much faster.
|
| At a glance, the article doesn't make it clear whether the
| "terahertz" speed refers to switching frequency or gain
| bandwidth (fT). You can definitely get transistors with fT in
| the hundreds of gigahertz range right now.
| itcrowd wrote:
| > digital signals have to propagate through multiple layers
| of logic gates, so the transistors have to switch much faster
|
| I don't think this is accurate. Are you saying that in
| digital computers each individual transistor switches faster
| than the clock rate of, say, 3 GHz? I think there is one
| clock signal that is distributed to all transistors and they
| turn on/off synchronously at this rate. The GHz number on the
| processor advertisement is the switching rate of all
| transistors, not some hypothetical 'system rate' which would
| somehow be much lower?? Please clarify or correct me if I am
| mistaken.
| xyzzy123 wrote:
| I think it's easier to see if you jump up 1 level of
| abstraction from transistors to logic gates.
|
| Imagine an adder made up of logic gates. The gates aren't
| inherently synchronous - they don't have a clock input -
| signals appear at their inputs and some time later
| propagate to their outputs.
|
| To make the adder synchronous you need flip flops at the
| inputs/outputs and a clock.
|
| If you squint a bit you can view most designs as blobs of
| async logic sandwiched between sync elements (gated by the
| clock).
|
| We can see that a signal might have to go through a lot of
| gates/transistors between flip-flops and so the gates (and
| their underlying transistors) will necessarily need to be
| able to switch faster than the clock.
| rbanffy wrote:
| This is the beauty of asynchronous logic: you don't need
| the flip flops and the clock - you need a yes-this-is-it
| signal propagating along the results.
| AdamH12113 wrote:
| You're mixing up time and frequency. For a signal to
| propagate through multiple logic gates in one clock cycle,
| each gate must switch in a fraction of a cycle. That means
| a single gate _could_ switch more often (higher frequency)
| _if it were by itself_. But it's not.
|
| (Technically, many gates do switch more than once per cycle
| since their inputs change at different times. But their
| outputs are only latched at the end of the cycle, so any
| extra switching is ignored.)
| mtlmtlmtlmtl wrote:
| Not an EE, but my guess is that current transistors can likely
| operate at a much higher clock rate than current chips.
|
| The problem is that when you pack them together, they get far
| too hot to permit dennard scaling to reach the limits of the
| individual transistor.
| tux3 wrote:
| This one's not because of heat, but because signal had to go
| from the beginning of a stage, through several transistors,
| to the end of the stage
|
| So the transistors switch fast individually, but the speed of
| the chip is limited by the slowest path in any stage, where
| you wait for every transistor on the path in series
| mtlmtlmtlmtl wrote:
| Ah, right, thanks for correcting me.
| foota wrote:
| Out of curiosity, how long are these paths generally?
| jiggawatts wrote:
| Low single digit millimeters for current chip designs.
|
| One reason that clock speeds are going above 5 GHz these
| days is that chips are getting smaller. That means
| shorter signal propagation distances.
| tux3 wrote:
| So, when I talked about the length of the path in number
| of transistors, I oversimplified a bit. The length of the
| path would be measured in nanoseconds (or even
| picoseconds).
|
| That number depends not just on the number of
| transistors, but also on the routing delay (are the
| interconnect wires between transistors long or short? How
| high is the resistance/capacitance?), and a lot of low-
| level details of the fabrication process that are
| extremely not public
|
| But say you buy a brand new CPU and it's clocked at 5
| GHz, you can easily get a rough estimate of how long the
| critical path is, since 1/5GHz = 0.2ns
|
| What you can't easily get is the speed of the transistors
| or the number of transistors in the critical path, that
| info is not public, and you could only make a very rough
| guesstimate.
| magicalhippo wrote:
| I recall reading some decades ago about dividing chips into
| separate domains that would commuicate asynchronously,
| precisely to shorten the longest path and increase the max
| frequency.
|
| It's my understanding modern processors do indeed do this
| to varying degrees.
| tux3 wrote:
| Yep, the term you might be thinking of is "clock
| domains". This is good if you want different parts of the
| chip to run at different frequencies, potentially saving
| a lot of power & gaining perf where needed
| deepnotderp wrote:
| Single transistor level frequency is different than chip level
| frequency.
|
| Each clock stage has many layers of transistors
| itcrowd wrote:
| For digital computers, clock speeds are single digit GHz. For
| analog circuits, ~100 GHz is achievable in silicon. E.g.,
| automotive radar chips, communication systems etc.
|
| This THz comment relates to analog circuits, which is
| supposedly around a factor 10 higher with this new tech.
|
| If you want to learn more, read about Fmax and Ft of
| transistors.
| sheepscreek wrote:
| > Why? We are single digit gigahertz, so terahertzes should be
| ~ 100 times faster?
|
| *1000 times
| imtringued wrote:
| PCIe 5.0 does 32 Gbit/s per lane, which means you need to run
| at least at 32GHz and probably more if you want to sample the
| signal more than once. So no, we are at way higher frequencies
| already.
| johntb86 wrote:
| Previous discussions:
| https://news.ycombinator.com/item?id=38912240 and
| https://news.ycombinator.com/item?id=38878780
| ajb wrote:
| Buries the lede a bit? Near the end is "Conventional GFETs
| [graphene transistors] do not use semiconducting graphene, making
| them unsuitable for digital electronics requiring a complete
| transistor shutdown. [...] the SEC [material] developed by his
| team allows for a complete shutdown, meeting the stringent
| requirements of digital electronics."
|
| As far as I heard before, this was the problem with graphene
| transistors, they had a nonlinear response but did not shut down
| the current flow, making them not useful for digital logic, only
| analog circuits. But, it's a while since I read about this so
| maybe someone else already achieved this before.
| j16sdiz wrote:
| That's the "bandgap" thing mentioned in the article. They
| exists, but very unreliable.
| singularity2001 wrote:
| Semi analog transistor would be perfectly fine for AI
| operations though? ( matrix multiplication, sigmoid, tanh etc )
| marcosdumay wrote:
| Analog or digital are properties of the signals you put on
| the circuits, not of the transistors.
|
| You can do digital manipulation with non-gapped transistors
| too. You just can't use the extremely intense when active but
| self-limiting designs we use today.
|
| Besides, unless we get some very creative new insights,
| analog computers are a dead-end.
| lbourdages wrote:
| I've been trying to find the source for a while, but I
| recall reading about a fundamental property of analog
| computers that makes them inherently unstable (as in, noise
| will always win on the long run), unlike digital computers.
| No matter how good the design is, little bits of noise add
| up in complex analog computers and the output is inexact.
|
| I guess my Google-fu is good enough, because I've been
| unable to find where I read about it.
| marcosdumay wrote:
| Are you thinking about the property of analog data that
| it can't be stored, reprocessed, or copied without the
| noise increasing?
|
| That doesn't make the computers unstable. It just makes
| the data less fit for long-term storage. And even then,
| people manage.
| lbourdages wrote:
| No, it wasn't about storage. It was really during
| calculations, you can't prevent the noise from affecting
| the results, from a fundamental level.
| fooker wrote:
| For any complicated calculation, you need to store and
| propagate multiple intermediate results.
|
| This is what goes wrong.
|
| error(x + y) > error(x) + error(y)
| imtringued wrote:
| Floating point calculation is "noisy" and yet there are
| models that use smaller and smaller floating point
| numbers without losing much accuracy.
| marcosdumay wrote:
| Oh, ok. You can't.
|
| I'm not sure you can find a citation though, it's like
| searching for a source that the sky is blue.
|
| Keep in mind that digital calculations have noise too.
| The digitization noise behaves in a completely different
| way, but any single computer has a finite precision
| whatever the technology behind it. Infinite precision
| doesn't exist on the real world.
| jari_mustonen wrote:
| Could this be the reason why human (and things with
| brains) need to sleep from time to time? Sleep would
| reset the accumulating noice from the brain.
| smolder wrote:
| It's not really clear what you mean by the brain
| accumulating noise. An analog computer can suffer from
| compounding imprecision, because error bars carry
| forward. We are analog computers in a vague sense, but as
| humans we aren't imprecisely crunching numbers all day
| such that our results are out of whack by nightfall...
| You could say sleep is like a reset for the brain, but
| that doesn't say much. Sleep is complex and relates to
| most everything else about an organism in complex ways.
| Qwertious wrote:
| Nah, humans just blank-out for a couple of seconds mid-
| task instead.
| magicalhippo wrote:
| Multiplying two numbers in an analog circuit requires
| taking the logarithms and add those, then converting
| back, or some similar trick.
|
| In practice this is done using non-linear effects of
| transistors[1], however the exact details of those
| effects are individual to each transistor and is also
| temperature dependent.
|
| Since the multiplication circuit relies on different
| transistors behaving identically, compensation circuitry
| and trimming is required, which will never be perfect.
|
| [1]: https://www.analog.com/media/en/training-
| seminars/tutorials/...
| persnickety wrote:
| Is it true, though?
|
| Look deep enough, and every modern digital circuit is
| emulated by an analog circuit, just because the
| components are analog in their nature, and the 0s and 1s
| are an interpretation of analog data. That includes
| digital computers.
|
| Does this make digital computers inherently unstable?
| Clearly, simple enough computations both of digital and
| analog kind are good enough to be useful. So there must
| be a breaking point further away, but on what axis?
| ajb wrote:
| A transmission line accumulates noise at it increases in
| length. Eventually the signal to noise ratio is too high.
| In old school analogue comms, the solution is to decode
| the signal to the digital domain before it reaches that
| point, which allows us to drop the noise. Then the data
| is reencoded back to a clean analogue signal again.
|
| In digital logic, this process happens at every gate.
| Hence the reliability of digital logic.
|
| Analogue logic doesn't do this. So analogue logic is only
| useful if the noise introduced at each step is lower than
| the error from your source data was already (at whatever
| point in the computation you have reached). If there is a
| way round this, I don't know it.
| persnickety wrote:
| There is a way around this: discretize your values.
| That's how analog calculations can be a basis for digital
| calculations.
|
| That's why I think the original comment was about a
| specific, limited meaning of "analog computation" that
| does not allow for emulating anything digital. But I
| struggle to come up with one that doesn't throw the baby
| of being universal out with the bath water of emulating
| digital computations.
| formerly_proven wrote:
| There's a term for analog systems using discretized
| values: digital.
| persnickety wrote:
| Exactly! And under that lens all fundamentals applying to
| analog also apply to digital: that they are inherently
| unstable and that noise will _always_ win in the long
| run.
|
| Which sounds at the very least imprecise to me,
| considering that I'm writing it on a digital (and
| therefore analog) computer.
| ajb wrote:
| In fact, Von Neumann proved mathematically that it's
| possible to build a reliable system out of unreliable
| components. But, modern digital logic uses a simpler
| mechanism: the thing you are missing is that noise _does
| not_ propagate or accumulate in discretize (digital)
| systems, as long as it remains below a threshold, and
| circuits are designed so that it is far below the
| threshold.
| imtringued wrote:
| Leaky ReLU is the best though.
| ajb wrote:
| Yes, analogue computing. It's a world of pain though, each
| individual operator in each individual device is going to
| have a slightly different level of accuracy, which is also
| going to be affected by temperature, so you need to learn a
| whole new set of analytical skills and operational practices
| to ensure that your model works correctly on each one at a
| customer location. And that's not even thinking about the
| testability at shipment of the devices being in spec, and
| that they are at all operating temperatures and over the
| lifetime of the device.
| happytiger wrote:
| I believe what you are referring to is called the Bandgap
| problem.
|
| Good explanation on the issue is here:
|
| https://www.allaboutcircuits.com/technical-articles/graphene...
|
| Convenience quote of relevant section:
|
| > Lack of Bandgap Despite being a fast and efficient
| transistor, the GFET does not have a bandgap. The gapless
| structure means that the valence and conduction bands meet at
| zero volts, hence making graphene to behave like a metal. In
| semiconductor materials such as silicon, the two bands are
| separated by a gap which behaves like an insulator under normal
| conditions.
|
| Usually, the electrons require some additional energy to jump
| from the valence band to the conduction band. In FETs, a bias
| voltage enables a current to flow through the band which acts
| as an insulator in the absence of the bias.
|
| Unfortunately, the absence of a band gap in GFET makes it hard
| to turn off the transistor since it cannot behave as an
| insulator. The inability to completely switch it off results in
| an on/off current ratio of about 5, which is quite low for
| logic operations. Consequently, using GFETs in digital circuits
| is a challenge. However, this is not a problem with analog
| circuits hence making the GFET suitable for amplifiers, mixed-
| signal circuits, and other analog applications.
|
| Multiple parties are researching ways to address these bandgap
| challenges, including techniques such as the negative
| resistance approach and the bottom-up synthesis technique of
| fabrication.
| LAC-Tech wrote:
| oh very cool. I remember hearing about graphene in inorganic
| chemistry 101 and thinking it that was the neatest thing in the
| world. That and carbon nanotubes.
|
| _De Heer says that it will take time to develop this technology.
| "I compare this work to the Wright brothers' first 100-meter
| flight. It will mainly depend on how much work is done to develop
| it."_
|
| Something to look forward to!
| foota wrote:
| It's amusing to think about something like a several thousand
| (probably more like billions?) transistor graphene based chip
| outdoing a trillions transistor behemoth.
|
| I don't know if that's possible in reality though, since things
| like cache space are important regardless of your clock speed and
| there's no point in being able to do fast logic if you can't pipe
| in enough data.
| foota wrote:
| Are there any niches for super high speed chips that it isn't
| possible to fill with silicon based chips? Would there ever be a
| niche for a small company making handfuls of them, or would it
| only be feasible at scale?
| Jweb_Guru wrote:
| Sure. Network switches for example have a pretty insatiable
| supply for processing speed.
| RecycledEle wrote:
| > This heating step is done with an argon quartz tube in which a
| stack of two SiC chips are placed in a graphite crucible,
| according to de Heer. Then a high-frequency current is run
| through a copper coil around the quartz tube, which heats the
| graphite crucible through induction.
|
| So they use a tube furnace?
|
| > "The chips we use cost about [US] $10, the crucible about $1,
| and the quartz tube about $10," said de Heer.
|
| Tube furnaces do not cost $10 except when you build it yourself
| and do not count the thousands of dollars of equipment you have
| sitting around.
| uSoldering wrote:
| They are talking about the price of consumables in the process.
| You also need a building and electricity and employees and a
| whole bunch of other stuff you can infer via deduction.
| GalaxyNova wrote:
| moore's law is not dead.
| klysm wrote:
| I don't think this has any relevance (at least in its current
| state) for digital compute.
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