[Coda]

Computer chips are the most well-known use of semiconductors.

The thing that makes a semiconductor special is the ability to control WHEN it's a conductor. Metals just always conduct, even if the conductivity is low.

Most elements (91 out of the 118 known elements) are metals. Metals characteristically lose their outermost electrons very easily, which means there's a free-flowing cloud of electrons inside the metal instead of a rigid electron structure. This is why they conduct heat and electricity so well. Metals are usually malleable (able to be pressed into shapes without breaking), ductile (able to be stretched into wires), and fusible (can be melted together). A nonmetal is anything that doesn't do these things. Metalloids have properties in between, though which elements are metalloids and which aren't isn't completely agreed upon (for example, some classifications say aluminum is a metalloid, most say it's a metal; some say carbon is a metalloid, most say it's a nonmetal).

I'm not using "bias" in a jargon sense here. I just mean that having an electric field means that electrons will have a strong preference to move in one direction and not the other.

I said "charge carriers," not "electrons." You can treat the absence of an electron as a mobile positive charge. THOSE have all gotten pulled out, too -- that is to say, all of the holes got filled up with electrons and there are no excess electrons hanging around either.