3 upvotes, 2 direct replies (showing 2)
View submission: Molecular Beam Epitaxy (MBE) : fabricating the nanoworld
So the thing is, MBE is really good at controlling layer-by-layer thickness, but lateral control is much harder. Think like a stack of pancakes where you can make the pancakes as thin as you want (pretty much down to single atom) but you don't have much control over the diameter.
Now, there are some well-known tricks for growing things like quantum dots and quantum wires, but there are limitations. Usually they're "self-assembled" which means you get really tiny clumps/wires of atoms on the surface, but they kind of randomly show up wherever they feel like. You can't control exactly where they are. Also these tricks don't work for every material. Still very useful, but it's a very far cry from the "dream" of 3D printing with atoms.
Another approach is to combine top-down and bottom-up. You can basically pattern a surface laterally with something like e-beam lithography, and then grow MBE structures from there. I think you can build 3D structures at the nanometre scale by kind of alternating between patterning from the top and then growing with MBE. But my impression is it's pretty challenging. It's much harder to get a good growth when you're not starting from a clean, flat surface. Not to mention you usually have to take things out of UHV to do the patterning, which means the surface gets dirty and you have to figure out how to clean it for your growth without destroying the pattern you just made. Again, very cool and useful, but still far from 3D printing atom-by-atom.
I don't think it's completely crazy to think that these processes might improve enough, or someone might figure out a way to do MBE + (something) to get something like 3D printing with atoms. But my personal feeling is it's probably more likely to be some other technology.
Comment by [deleted] at 15/09/2023 at 13:45 UTC
1 upvotes, 0 direct replies
Yeah to have a good growth, you need a clean surface or you will form islands and have very inhomogenous films which is very detrimental to the physical properties aside from the fact that most of the time you can't really control this kind of defects
Comment by ReasonablyBadass at 15/09/2023 at 12:00 UTC
1 upvotes, 1 direct replies
Interesting. Thanks for the answer!