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While reading this paper (suggested by @Janice here), I came across the following line:

Surface reconstruction is known to be extremely important for Si, the material of 20th century electronics. However, surface reconstruction has been much less studied for graphite. One of the reasons might be graphite's limited use in electronics because fabrication of ordered graphite substrates is difficult.

(emphasis mine)

I've always believed that graphite isn't much used in semiconductor tech since it isn't a metalloid and conducts in an entirely different manner, probably making doping not work. This reason is new to me, but quite interesting.

I can sort of guess why "fabrication of ordered graphite substrates is difficult" — I'm not too sure though.

At any rate, I'd like to know more about it. Exactly why is such fabrication difficult?

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  • $\begingroup$ Also, a good demo for the semiconductor aspect of it is to draw out a fairly thick (5cm x 1cm) pencil line on a piece of paper. If you have a voltmeter handy, check the resistance across your "block" lengthwise. I would guess it would be on the order of a few hundred ohms, but don't quote me on that -- you can probably calculate it from the resistivity of graphite and the length. $\endgroup$
    – jonsca
    May 20, 2012 at 8:51
  • $\begingroup$ What do You mean with "metalloid"? $\endgroup$
    – Georg
    May 21, 2012 at 22:00
  • $\begingroup$ @georg metalloids conduct via a conduction band--same as metals. They can be doped easily. Graphite works by the delocalization voodoo, so it's completely different. Doping may only work if the dopant can participate in the delocalization. (What I think, anyway) $\endgroup$
    – ManishEarth
    May 22, 2012 at 2:05
  • $\begingroup$ @chris oh, that's my mistake--the pdf is locked to prevent copy-pasting, so I manually copied it. Yeah, I know that graphite isn't a metalloid. $\endgroup$
    – ManishEarth
    May 26, 2012 at 5:51
  • $\begingroup$ I don't really agree with their reason, but it might have to do with reaching a high enough purity... perhaps a higher mp of carbon over silicon is a basis for this?? $\endgroup$
    – Chris
    May 26, 2012 at 5:54

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Graphite is a semimetal, and no more mambojumbo than with metals, but it doesn't do anything with the problem. Silicon/silica can be melted, purified, doped, can single crystals grown, can oxidize the surface, making the silicon semiconductor an silica insulator. By "can" I mean that engineeers know well tested methods, optimized for half a century.

Graphite cannot be reasonably melted, cannot grown to single crystals, cannot doped with similar techniques, highly anisotropic, so cutting maybe an issue, and when you make thin layers, it is hard to oxidize in a controlled way to make an insulator out of it. The resulted oxides are semiconductors, and there is a large variety of local structures that can appear with different electronic properties. By cannot I mean that no one really though about these problems until the last decade, so there might be equivalent solutions with e.g graphene, nanotube or other nanocarbon structures.

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