How come we can grow nanowires? Semiconductors

Question

I'm not a physicist by background but I'm interested in semiconductors and am trying to understand third generation semiconductor material technology. In some of the roadmaps for the 2nm and 3nm chips nanowires are shown to be used. I've read a couple of papers on Gallium Nitride nanowires but I am curious why it is possible that such fine structures can be grown? And with enough precision, reliability, and volume that scientists think they can be used all over the world.

I suppose this might be a question for materials science but I don't really know!

I have encountered defect energies confinement theory and quantum confinement theory in the papers.

I know it must be hard to explain this to someone without a background in the area but I'm genuinely curious about this topic and I don't mind hearing about technical details - or if you have some links you could provide so that I can learn more about it that would be helpful too :)

Kya

Answer 1

It is a difficult question, since there exist many types of nanostructures, largely depending on the techniques used to fabricate them. I will cite a few, without giving particular focus to nanowires:

• Molecular beam epitaxy is a well established technique for fabricating computer chips. It is widely used for creating two-dimensional semiconductor structures (two-dimensional electron gas), which can be further fashioned into any shape (dots, wires, etc.) by depositing metallic gates on the top of the structure and applying negative potential to them (split-gate technique).
• Self-assembly or colloidal techniques: a thin layer is deposited on a substrate semiconductor of different type. Due to the material properties mismatch, boundary effects, etc., the layer collapses and forms small drops or strips, i.e. quantum dots or quantum wires.
• Molecular self-assembly molecules/atoms from a gas phase crystallize on a seeded substrate in a form of columns. Depending on the height of such a column, it will be either a dot or a wire.
• Atomic deposition One could simply deposit a chain of atoms (i.e., gold atoms) to form a wire.
• Carbon nanotubes and fullerene buckyballs are naturally made quantum wires and quantum dots (although the methods for their synthesis may resemble molecular self-assembly).
• Finally, one could simply suspend a molecule or a chain of molecules between electrodes.

Disclaimer: This is by no means a complete list. Moreover, being a theorist I am probably rather sloppy in terminology and descriptions.