In the context of the band theory of solids, semiconductor character is in general attributed to certain crystalline solids with its Fermi level lying in the gap. In amorphous materials, where the gap may be full of electronic levels and therefore is not well defined, many levels correspond to localized states, and frontier between dielectric and conductor is poorly defined, and relays on the concept of 'mobility edge,' the energetic level at which electronic states get delocalized. In this case we still speak about semiconductor amorphous materials. I wonder if a gas may behave in a similar way under certain conditions. Does it make sense?
It's an interesting question. From what I know the "band gap" in amorphous semiconductors arises from the fact that even though there is no long range order, there are still preferred bond angles and lengths and therefore short range order. I think that if there is order whatsoever, there will not be a band gap. There are some amorphous solids where this is true and these are not semiconducting. I think it is quite well explained in Mott&Davis book.
I would think there is no short range order in gases so it wouldn't make sense. Also, I suspect that if there are moving charges in a gas when an electric field is applied (which is required for conduction of any sort), it would be ionised gas atoms that move rather than electrons moving within a "stationary" gas cloud. Simply because atoms in a gas have large gaps between then and it is easier for an atom with a charge to move than for a charge to move from one atom to the next.
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