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"Black Silicon" Advances Imaging, Solar Energy
waderoush writes "Forcing sulfur atoms into silicon using femtosecond laser pulses creates a material called 'black silicon' that is 100 to 500 times more sensitive to light than conventional silicon, in both the visible and infrared spectrums, according to SiOnyx, a venture-funded Massachusetts start-up that just emerged from stealth mode. Today's New York Times has a piece about the serendipitous discovery of black silicon inside the laboratory of Harvard physicist Eric Mazur. Meanwhile, a report in Xconomy explains how black silicon works and how SiOnyx and manufacturing partners hope to use it to build far more efficient photovoltaic cells and more sensitive detectors for medical imaging devices, surveillance satellites, and consumer digital cameras."
It's African-American Silicon, you insensitive clods!
Now I'm going to have to counteract this worrying news by expediting my research on black tinfoil.
So how exactly are they going to become 500X better at gathering light?
This is another company using the mystique of "Trade secrets" to attract capital. If this is as good as they say, they wouldn't have any secrets and would spill the beans.
I think they have found some weaknesses that restrict the usefulness of this technology. Perhaps sensors made with this technology must be supercooled in order for them to function properly (i.e. perhaps this technology amplifies thermal noise by dozens of times).
Not all photons have the same energy (wavelength), and this is for precision imaging not power generation. Note it's more "sensitive" not more efficient.
"They were pure niggers." – Noam Chomsky
... again. I love solar power, and I realize that it progresses in small increments. But there have been so many stories of "break through" improvements that I don't really care until a profoundly more efficient product is made. Black silicon have twice the sensitivity to light that regular silicon does, which is great news for digital cameras and night vision scopes. I might be great news for solar power, but tell me about it once you have a working prototype with a noteworthy efficiency improvement.
We are all just people.
The efficiency of a solar cell is equal to the power absorbed by light divided by the power that is actually sent to the circuit the device is attached to. So if the sensitivity of the collector increases 500x, then there is likely going to be a major increase in the power supplied by the cell. This has nothing to do with the efficiency
Read carefully: they said 500x more sensitive than silicon, not 500x more sensitive than PV cells.
It's a bit like if they said that by reacting hydrogen with oxygen, they created a compound 700 times denser than oxygen. That doesn't mean it's 700 times denser than the densest material known.
Science writers who don't know what they are talking about annoy me,
There's an interesting irony to SiOnyx's business: a large chunk of the semiconductor industry's effort over the past 50 years has gone toward making silicon as pure as possible. But now SiOnyx and other companies are showing how useful--and perhaps profitable--it can be to craft silicon devices with impurities, defects, and unconventional structures.
A pure silicon crystal ingot and a doped silicon wafer are entirely different. You want a pure crystal to grow the ingot as large as possible. To make silicon useful you take the wafer sliced form the ingot, ant it has to be doped (ie add impurities) amongst many other steps.
LetterRip
This only increases sensitivity, sorry...
No sig today...
Forcing sulfur atoms into silicon using femtosecond laser pulses...
Who sits around and dreams up a process like that? "Hey, I wonder what would happen hitting sulphur ions with a femtosecond laser pulse?" Just bizarre what some people sit around thinking about all day.
That's our life, the big wheel of shit. - The Fat Man, Blue Tango Salvage
Sensitivity may refer to the ratio between light and dark current. Obviously one can't knock out 500 times more electrons with the same amount of photons in this material because typical silicon photodetectors aren't THAT bad. The increase in efficiency may only be a few percent for reasons I won't go into.
It does not, however, increase your sensitivity to humor.
The tough black silicon that won't cop out when there's light about.
I'll take your 1000 - 5000 % and at least qunituple it. There's other similarly exiciting new releases each week on solar. Within the decade we should have 25,000% efficient pannels though it could go as high as 1,000,000%. Phenomenal indeed!
Silly me.
No sig today...
There are already solar cells (albeit expensive ones) that are rated at 40% efficiency. Going on the low end of this how can you improve 40% by even 100X and not have perpetual motion? Heck, you think we had a Global Warming problem before, imagine how hot things are going to get once we start generating 4000% of all received solar energy.
"It's the height of ridiculousness to say for those 9 lines you get hundreds of millions."
I might be great news for solar power, but tell me about it once you have a working prototype with a noteworthy efficiency improvement.
From what I've read this story is more about image sensors, but for solar cell applications: I don't understand the fuss about all these 'breakthrough efficiency record' stories. For all but a few applications (think satellites, pocket calculators etc.) efficiency doesn't matter. There is no shortage of sunlight, and therefore no need to turn a maximum of it into electricity. What matters is price per generated electric power ($/Watt), and how long the solar cells will last.
If I'm not mistaken, the solar cell market is hitting the 1 $/Watt mark around now, and growing at what, 10% ? 20% ? 50% per year? Wake me up when solar cells become cheaper than roof tiles, or provide a return on investment in <5 years (for average households), and will last decades after that. Then you have a breakthrough.
If you build a 3-D version of this in a pyramid shape, you could either destroy the Sun (something that Man has yearned to do since the dawn of time), take photos of the future or the past, or, if you're really ambitious, hook it up to a very powerful laser and spin it, and you could vaporize a human target from orbit.
Either way, it sounds like it's time to party with the ladies from the local cosmetology school. They're so impressive; I don't think I could handle that zero gravity stuff.
But there have been so many stories of "break through" improvements that I don't really care until a profoundly more efficient product is made.
Some years back, I read an article in an old magazine (I think it was a 1960's Popular Science) about a new method of blowing glass resulting in "near unbreakable" bottles. It went on excitedly for page, after page, talking about the new era of safety that this kind of glass could behest - glass that doesn't easily break - you could drop your soda or medicine bottle and it wouldn't shatter!
Intrigued, I spent an entire afternoon at the local University library trying to figure out exactly what happened to this miraculous technology! I even did some searching (AltaVista) on the then new-fangled Internet. The truth rather surprised me...
This "breakthrough" technology that had gone invisible was part of my everyday life, including the bottle of Diet Coke I was then slurping from! It had become so common that virtually nobody produced the old-fashioned fragile bottles and glass anymore!
That's why it works to have coffee tables with glass counter tops. That's why restaurants can get away with the sterile, easily cleaned, hard-to-scratch glass overlays on their tables. Next time you are at a corner market and see the glass countertop with the items for sale inside, think about that article in the ancient Popular Science article.
Once breakthroughs actually become available, they don't seem like breakthroughs - they quickly just become part of the landscape, and people don't notice them, anymore. This is why the "Intelligent Design" idiots can get out of their incredibly complex, affordable, high-tech SUVs and then announce that Science has it all wrong. Once it's routine, it no longer seems like such a big deal.
Proof? Affordable, thin-film photovoltaics is still largely considered a "breakthrough" technology. But there's a company doing it now, today, affordably. Alas, while they are growing as fast as they are able, all their production capacity is already sold to germany. I'd suggest you read up on it.
High tech is introduced slowly. At first, the high engineering cost can only be paid in niche markets where the return on investment is fat. But as the original engineering cost gets paid back, and as the technology itself is matured and tested, the cost of implementation drops rapidly, so that it applies to more and more and more niches. By the time it's available for common Joes like you and me, it doesn't seem like such a big deal, and we are left wondering "where are the breakthroughs?" from our satellite/GPS navigated, MP3 playing, fuel-injected, ABS-brakes protecting, vulcanized rubber-tired, air-conditioned, hybrid gas/electric, high-tech wonder machine.
Where are the breakthroughs? Look at the beer bottle in your trashcan.
I have no problem with your religion until you decide it's reason to deprive others of the truth.
As far as I know, efficiency can apply to any resource, including money.
We'll effectively be stealing energy that DIDN'T strike earth! Sucks to be anyone else harvesting energy from Sol...
There were two other discoveries for silicon (such as 3d structures) that claimed similar improvement. So do you get x1,000,000 improvement or only x300 improvement? Or are the improvements going to negate each other?
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Just to be a bit more explicit, sensitivity probably refers to one of two things.
The first would be an increase in quantum efficiency; that would be an increase in the ratio of photons detected to those impacting. In a photovoltaic cell this would lead to improved efficiency. Current scientific detectors, that I've looked into anyway for a research project I'm involved in, max out at maybe 70%, with most reasonably priced ones being 25%-35%. (The 70% ones tend to be things like photomultiplier tubes which require power input to achieve a high reverse voltage, so they're certainly not useful for PV cells.)
The second aspect would be to decrease the noise or dark count so that its capable of detecting dimmer and dimmer light sources, and in order to get the > 100% improvements this is definitely a large aspect of what the new method has done. Unfortunately I know more about the applications and figures of merit than the semiconductor stuff, so I can't say much about this other than I hope this opens up some new application possibilities.
The problem with most uncooled imagers isn't insufficient sensitivity any more. It's thermal noise. Unless this improves the S/N ratio, it won't help for uncooled imagers. That's why digital cameras which increase sensitivity in darkness show more and more noise as less light is received.
Cooled imagers, though, as in astronomy and fancier night vision equipment, might benefit. Cooling is done to reduce the random photons from heat within the imager. So cooled imagers do run into the sensitivity limitations of silicon, and might benefit.
But that's an exotic application. Cooled imagers are found mostly in military, space, and astronomy. Some require liquid nitrogen. It's not a mainstream technology.
Black silicon has long been known in the semiconductor processing industry (usually as an undesirable effect). All high performance silicon solar cells already use some kind of texturing to increase light absorption through scattering and optical confinement, and indeed do look quite "black".
So it's unclear if this particular approach will be significantly better. Black silicon is produced by a plasma etch process, which I think is more expensive to do than the plain old anisotropic wet etch you can use to pit the surface of silicon.
Black Kryptonite? Doesn't that turn out to be Spike The Vampire on Steriods?
Red Krytonite? Now that turns you on to more energy and wild behaviors! Let go your wild side.
Green Krytonite? Well, that's painful even though it's all environmental green it's a disaster for everyone who comes into contact with it.
White Krytonite? Known to build crystal fortresses and cities as long as you want to live in solitude.
So bring on the Black Silicon! Let's absorb the Sun's rays and make it happen! At least we'll super power our devices with all that Yellow Sunshine and recharge our batteries!
It must've been at least 6 or 7 years ago when I read about this technique, and how it was accidentally discovered, in an article. Why has it taken so long to reach the market?
If this is as good as they say, they wouldn't have any secrets and would spill the beans.
The fundamental research was done a long time ago(with picture of prototypes); I've read articles about it in Electronics and Wireless World several times over the years, so it's hardly a secret. Any potentially patentable critical element is going to be kept under wraps, obviously.
I think they have found some weaknesses that restrict the usefulness of this technology.
Or they spent 3 years on R&D fixing those weaknesses, like the article says.
Further information of note from the NYT article:
So we're told:
1- There's a decade of peer-reviewed research behind the technology.
2- They have funding and partners already.
3- They're shipping parts now, not at some unknown time in the future.
Either this is real, or Dr Mazur et al are engaging in an exceptionally elaborate, very public and career-ending series of lies (and it's not as though SiOnyx will be a paying proposition if the tech doesn't work). The part of the operation that does look suspect is their web site (Flash warning), but that doesn't prove anything about the physics involved.
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Very good point, but the attack on Intelligent Design doesn't _quite follow (sadly!).
Not that I am a fan of ID. Not on the same page at all. Perhaps not even in the same library. But there is nothing illogical about considering organisms to be 'designed' the same way that technology is.
I think it is because complex design is so familiar to us that it is easy for some people to assume that's how biological systems came about.
In fact, biological structures are very different to most human-designed artifacts. They self-assemble, are wet, made from millions to trillions of tiny parts, exploit chemistry to an amazing degree, and so on.
Ironically, it is only now we are starting to design systems that are nearly as complex as biological ones that most people are cut off from the design process and many are probably unable to understand modern high tech.
So, yes the ID advocate in a high-tech SUV is ridiculous. What he sees is the large-scale parts (wheels, body, seats) and fails to notice the tiny parts in the airbag trigger.
Just a note, but you have no idea whatsoever what a true ROI is unless you personally have a signed ironclad contract with your current electricity provider as to their "cost per watt" delivered for your uses, say a 5 to 20 year locked in price. And with that said, because for residential purposes this does not exist, even then it is still apples and oranges, you never have a ROI with your normal electricity provider because of how the pricing and delivery model is set up, no matter how much money you give them over the years, that bill is never paid off. It costs you money, you never build any equity whatsoever. Want a car analogy? You can lease a car, or buy it. Leasing is cheaper up front and for the payments, but if you want to drive, you'll be making that payment forever. If you buy, it is higher upfront and the monthlies are higher, but eventually it is paid off and you can garner several years cheaper driving by only doing normal maintenance, usually. A house? You can lease/rent forever, or buy it. One way gives you a place to crash, plus builds equity, the other just gives you a place to crash. So right now, even at today's solar prices, for most people you can build equity, get it paid off, and have x-years electricity for just the cost of maintenance. That is a big variable of course, I cannot make any general price point comparison, and it depends on how much sweat equity you are willing to assume with the installation, it can run as high as 50% or more of the quoted price from some dealer if you do none of the install labor. If you are handy with tools, you can do roughly 90% of the install yourself, and only leave the first design and recommendations and then the final connections to a licensed electrical contractor, then present it to the inspector.
It seems that the subsidies in some countries, especially Germany, are keeping prices for photovoltaics panels up. Companies like Nanosolar can sell their panels for way more than manufacturing costs, because the subsidies are designed to make more conventional and expensive panels economically viable. There is a yearly degression built into the legislation, but so far it does not keep up with improvements in manufacturing.
I expect this situation to change drastically once the German market reaches saturation. At that point, real competition will kick in and panel prices will drop to a price where they will be attractive without subsidies. And Nanosolar are not alone in developing cheaper panels.
For instance, there is First Solar: http://www.firstsolar.com/
C - the footgun of programming languages
I'm sorry, I fail to see where the car fits in.
Semi-automatic amateur armchair Australian philosopher; conjecture ready at any moment...
You are right, that is the idea. From Behe's book "Darwin's Black Box" (a pretty stupid book) the 'problem' is that systems can be "irreducibly complex". That is, like the mousetrap - remove or change any part and it stops working.
The problem again (and since Behe's is a biochemist he is either stupid or lying if he doesn't understand this) is that nature builds her mousetraps in a very different way.
All previous 'versions' of any particular mousetrap (or other design) HAD to work. Small changes to them, including replacing parts or modifying parts were made, and those mousetraps that failed to catch any mice were rejected (died off).
This is only possible with systems whose parts can be replaced with slightly similar ones, and still sort of work. Evolutionary systems have evolved to be evolvable.
So, it's not the self-assembly, but the mutability of natural systems that is under dispute. Most biologists understand that natural systems can change quite radically - species evolution - while a few ID-ers just don't get it. Their loss; natural systems are truly astonishing.
They already spilled the beans - femtosecond laser pulses against silicon wafer in sulfur hexafluoride gas.
The problems probably are:
1. femtosecond laser pulses aren't exactly easy to make
2. the power density of the beam (if they increase the spot size, the power density goes down, meaning it's more costly and difficult to expose larger portions of the wafer at once, hence increasing time and cost)
3. sulfur hexafluoride - ummm hexafluoride anything is probably not the safest thing to deal with, hence - increasing cost
4. effects of oxide formation post-processing probably increases problems
5. thermal noise ... probably not much of an issue, plus I don't think they're talking about far IR photons, just IR that would normally be picked up in a GaAs detector
6. there is no mention of what wavelength of laser light they're using, so if it's something in the UV range, they'd need more expensive optics, increasing costs yet again.
I just want these SiOnyx people to do this with Uranium Hexafluoride. I want them to do it NOAW!
That should have a beautifully large cross-section, gobbling up lots of photons, and would give the nuclear industry something to do besides fission. This is just a guess, maybe there's some fucked up reason UF6 just wouldn't work for this purpose. I just like the idea of increasing the absorption band of photovoltaics.
meh ... back to reading the Modern Physics textbook.
The company name is a good choice, it sounds like Psionics, which implies of Psi, the Greek letter used to represent wavefunctions, on top of the onyx for black.
I'm one step closer to psionic powers!
:(
Wait, nevermind, they said SiOnyx.
If you can read this, I forgot to post anonymously.
If you read the journal articles http://dx.doi.org/10.1016/j.mseb.2006.10.002 you'll find that this process esentially creates a large number of impurity states at the center of the band gap, creating an impurity band. What this means is that light is absorbed very very fast, but then its also turned to to heat very very fast. In other words you can excite electrons but that electron will decay back down before it creates any current. This could still work for a photodetector because you can apply a voltage to sweep out the excited carriers before they recombine/decay but not for a solar cell since you want to generate power.
It will most likely be many years before this turns up in a product or it may not even happen at all as work on this progresses and the details are sorted out or not. It is still interesting to some people before you can buy it at Walmart or your local equivalent and you don't have to read the article if you don't want to.
Efficiency counts in terms of size. Yes, if we need more power, we can build bigger collectors. However, in many cases space=money. Moreover, convenience=easier sell=more money.
There's already plenty of little solar gadgets for charging your cellular or whatever while camping, those wouldn't work too well if you needed an area the size of a football field to get enough power. More efficient collectors can mean (in general) that you can get *the same* amount of power (as a less efficient collector) in a smaller area, although with many techs there may be a minimum to that as well.
Imagine if you could power your air-conditioner with a simple collector that was the size of, well, the top of your air conditioner. That's convenient, efficient, and sellable. In fact, even if it doubled the cost of the unit itself (for a standard window unit, $150-400), the convenience - especially for mobile purposes - and savings-over-time feature (not to mention the gizmo feature) would probably make it a good sell.
100-500 sounds like a lot to me, and I'm wondering how close is that to the sensitivity of the human eye's cones and rods? And are we talking about full spectrum sensors or a narrow band? Getting anywhere close to the power of the eye would have a profound effect on the photographic world and doubly so for motion photography.
Support bacteria, the only culture most people have.
That 40% is at some specific wavelength (or band). Generally speaking there are vast swaths of infrared light that standard Si PV cells don't collect. These areas of the spectrum could easily be absorbed 500x more than they already are.
That being said, I don't think it's 500x more efficient, just 500x more sensitive. That simply means that the signal/noise ratio is 500x (27dB) higher than before.
dom
The sensitivity they are referring to is the amount of electrons released by the incident light - Amps of current per Watt of sunlight. Sunlight has a broad spectrum, and this technique allows more of the infrared portion of the spectrum (which is a lot) to cause electrons to flow.
However, and this is important, they achieved this by lowering the bandgap energy of the silicon. Why is that important? Remember that power, when it comes to electronics, is current times voltage. The voltage of a solar cell (open circuit voltage) is more or less the bandgap energy (divided by one electron charge). So, yeah, they get more electrons to flow for the same amount of incident sunlight, but the cell's voltage has also been lowered. Do you end up with more or less power as a result? Does the greater current overcome the lowered voltage? Since they haven't actually published data on a solar cell made from this technique, there isn't really a way to tell for certain.
My guess is that they won't be able to get vast power gains - possibly lower ones. The reason for this is that, right now, one photon with energy greater than the bandgap energy has a chance to create one electron-hole pair. If the photon has more energy than the bandgap energy, it doesn't make a correspondingly more energetic electron-hole pair. Even if the photon had twice the bandgap energy, it can't make two electron-hole pairs. So, a blue photon creates as much useful electrical energy as a red photon, despite the fact that the blue photon has more energy in it. One can play around with the bandgap energy of the PV cell to make better use of the high energy photons, but at the cost of excluding lower energy photons like infrared and red. More info here. This is why the solar cells with greatest efficiency are actually multi-junction cells - several solar cells with different bandgap energies stacked on top of each other, each tuned to a different portion of the solar spectrum.
The article mentions how these guys should be able to use their black silicon to create multiple electron-hole pairs from a single photon. In order to do that, however, they have to provide a bias voltage. In that case, the solar cell is sucking power, not producing it. That's fine if what you want is a very sensitive photo sensor - it's basically a solid-state photomultiplier tube. It's not a way to generate electrical power.
I think he was talking about making dihydrogen monoxide which the car would then run on.
They ARE out to get you simply because They are in it for themselves and they don't care about you.
Some of the really old b&w programs had 10x the science I've seen on TV today.
They ARE out to get you simply because They are in it for themselves and they don't care about you.
Often even when they were wrong it was because science has advanced.
"If you would be a real seeker after truth, it is necessary that at least once in your life you doubt,as far as possible
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