I understand how holes are treated as independent mobile charges by imagining each cation left behind when an electron jumps to an adjacent hole as “moving” positive charges (holes).
I also understand that conventional current refers to the flow of “extra” electrons not part of a covalent bond pair (like in an n-type semiconductor) flowing in the conduction band, and that the flow/jumping of electrons from one bond pair to a hole in an adjacent bond pair refers to the hole current in the valence band.
But I don’t understand why hole currents are neglected in conductors. In conductors, valence bands and conduction bands are said to overlap, but what exactly does this mean for the movement of electrons? In solid states, we say that metals consist of a sea of mobile electrons in a lattice of fixed positive ions. Is this the reason we say there’s no hole current? Because the leftover cations can’t really move (even virtually, since there’s no adjacent bond pair “jumps”)?
Am I confused about what hole current is or what conduction current is? Because the same question for conductors could be asked for the majority charge carriers in n-type semiconductors. How exactly does not being part of a covalent bond and lying in an independent orbital give these majority charge carriers more “freedom”? The cations that these extra electrons leave behind when they flow freely are similarly fixed in the lattice, but why can’t that one empty orbital from which the extra conduction electron emerged be treated as a hole too? Why reserve that term only for vacancies created in bond pairs? Is it because no electrons can actually jump into these lone vacancies, thereby ensuring that the vacancy stays with the same atom?
I feel like I’m very close to the answer but I can’t quite get it. Hopefully, my chain of reasoning is clear.