Slashdot Mirror
Behind the Scenes At a Quantum Dot Factory
Tekla Perry writes: In a nondescript office complex in Milpitas, Calif., Nanosys is making enough quantum dots to populate 6 million 60-inch television screens annually. "The process goes on in what looks like a microbrewery. In about half a dozen large metal tanks ... Nanosys combines cadmium and selenium and adjusts the temperature, concentration, and catalysts added to force these precursors to combine into stable crystals of cadmium selenide. Then, by readjusting the conditions, the system stops the formation of crystals and triggers the beginning of crystal growth. A computer controls the process according to a programmed “recipe;” staff members monitor the growth of the crystals by shining light on them and measuring the wavelength of the fluorescence; the smallest crystals don’t fluoresce at all, then, as the crystals get larger, the wavelength changes. Nanosys stops the process when the fluoresced light hits the target wavelength, which varies depending on what particular display industry standard that the batch of film is designed to meet."
Isn't that what got you into the secret room in Adventure?
I have been reading /. for far longer than my ID # indicates. IIRC, it was 1999 when I happened upon the site, I just didn't bother to join, because I never had anything useful to say. Back then it was "News for Nerds, Stuff that Matters." Unfortunately, that guiding mantra no longer adorns the /. bannerhead and we are poorer for it.
This submission is a perfect example of "News for Nerds, Stuff that Matters." The summary doesn't tell you everything, you have to click through and read the article to get the true value of it. I read the article and it was very informative. I learned interesting information from it. It wasn't just interesting, I might actually use that information in the future.
Thank you for perking up my day with interesting information and giving me hope that /. will continue to be a site to return to for quality information and news.
The button to Submit a story is right in front of your nose a the top of the page.
Unless you're implying the editurs are idiots and ignore perfectly nerdulent story suggestions.
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
TFA discusses this, and they are working on cadmium-free dots, but they are harder to produce. They use indium and phosphorus for those.
Yes. The article also continues to further explain that the cadmium-free dots are less efficient, which makes them less-desirable to the display manufacturers.
Also, to GP, the CEO of the profiled company notes in the article that they do not release any Cadmium in the production of the quantum dots, but they have no control over how the displays are disposed of when they are no longer wanted. Considering the environmental consciousness that they are stated to show, I'm sure the company would love to get those dumped displays and get that Cadmium back, rather than letting it being lost in the environment.
that's racist. please use "native americium" going forward.
A few tens of nanometers in diameter. Dots emit light at (more or less) a single frequency (it's actually Gaussian around the chosen frequency.) To emit that photon, the dot has to absorb a photon of higher energy. Since right now dots are absorbing visible, it's energetically possible to emit in microwave or radio frequencies. While I believe it's possible to do so, existing methods may be more efficient (energy-wise or cost-wise), or we may not have discovered dot materials that allow for those emission frequencies.
Short answer is no. Although there are plenty of other semiconductor devices that can operate in the microwave.
The "quantum" part of quantum dots is that the effective bandgap of the semiconductor, which controls the wavelength of luminescence, is increased by quantum confinement. Google particle in a box for more information.
"How do they get the green light from EPA in the first place?"
By shining blue light on green quantum dots, I guess.
Bert