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Seconded; molecular beam epitaxy is certainly not an industrial technique! Here's a picture of some MBE equipment via Google: http://www.sandia.gov/LabNews/LN0

by Osmium 14y ago

Seconded; molecular beam epitaxy is certainly not an industrial technique! Here's a picture of some MBE equipment via Google: http://www.sandia.gov/LabNews/LN06-16-00/images/beam_pix.jpeg http://www.sandia.gov/LabNews/LN06-16-00/images/beam_pix.jpe... It's large, complicated, expensive, difficult to optimise and run, and ultimately can only grow very small amounts of (admittedly high quality) material (relative to the size of equipment and the time it takes to do the growing). On a simple level, it works by creating a "beam" of atoms which you can deposit onto a surface to grow your crystal layer-by-layer: this most definitely is not something that scales well to industrial sizes.

jpdoctor 14y ago
> molecular beam epitaxy is certainly not an industrial technique! Of course MBE is an industrial technique: A fair fraction of the semiconductor lasers on the planet are made this way, and probably a decent fraction of the microwave power amps for cell phones. The thing that is interesting here: There is an optimal stoichiometry for electron velocity in InGaAs, and it is hard to lattice match with a substrate for that composition. Usually there is magic in the buffer layers. (IIRC)
- Osmium 14y ago
  Thanks for the correction; I had the article in mind, talking about it replacing Si transistors, and can't really imagine MBE being used to produce millions of chips, though I'd be happy to be wrong about that.
  - jpdoctor 14y ago
    > and can't really imagine MBE being used to produce millions of chips Cell phones are example application for millions of chips. There's really nothing that magic about it. What is difficult is the large-scale integration of transistors, which is why you don't see CPUs (for example). There's a number of reasons, mostly relating to the nature of III-V materials. One example is the lack of a decent oxide: SiO2 is god's gift to electronics. However, Si is not a direct bandgap, so it is next to useless for devices involving light. It's why the bazillions of lasers on the planet are III-V.

by Osmium 14y ago

jpdoctor 14y ago

> molecular beam epitaxy is certainly not an industrial technique! Of course MBE is an industrial technique: A fair fraction of the semiconductor lasers on the planet are made this way, and probably a decent fraction of the microwave power amps for cell phones. The thing that is interesting here: There is an optimal stoichiometry for electron velocity in InGaAs, and it is hard to lattice match with a substrate for that composition. Usually there is magic in the buffer layers. (IIRC)

Osmium 14y ago
Thanks for the correction; I had the article in mind, talking about it replacing Si transistors, and can't really imagine MBE being used to produce millions of chips, though I'd be happy to be wrong about that.
- jpdoctor 14y ago
  > and can't really imagine MBE being used to produce millions of chips Cell phones are example application for millions of chips. There's really nothing that magic about it. What is difficult is the large-scale integration of transistors, which is why you don't see CPUs (for example). There's a number of reasons, mostly relating to the nature of III-V materials. One example is the lack of a decent oxide: SiO2 is god's gift to electronics. However, Si is not a direct bandgap, so it is next to useless for devices involving light. It's why the bazillions of lasers on the planet are III-V.