![]() ![]() ![]() (See, the electrons aren't actually the opposite of holes. In the same way that protons aren't positive ions, electrons aren't negative ions. Like any conductor, the p-type material is overall neutral, (negative borons and positive silicons,) even though it's filled with mobile charges.Īre electrons actually negative ions? Nope. "Lack of electrons" just means "un-cancelled protons.") The holes move the positive ionization moves, but the protons themselves stay still. (Only protons can supply positive charge. They really are positive-charged particles. When we say "lack of electrons," we really mean "initially neutral atom, then an electron is removed, leaving an exposed, un-cancelled proton a positive ion." Holes are actually the un-cancelled protons of the silicon crystal lattice. Is vacuum therefore made of positive ions? No, that's silly.) In other words, inside p-type semiconductors, only the "ionization" is moving around, while each positive-charged atom remains locked into the crystal lattice.Īlso, take careful note that in physics, "lack of electrons" isn't a thing. The material becomes a grid of unmoving negative borons, plus an equal cloud of mobile positive-ionized silicons. Thermal vibrations knock the mobile charges around, so the opposite charges soon are widely separated. At the same time the negative boron ion remains trapped. The boron now has excess negative charge (more electrons than protons,) while the silicon has excess positive charge (more protons than electrons.) But then the magic happens: that positive silicon ion can grab an electron from a silicon neighbor, ionizing the neighbor while becoming neutral itself. This creates a pair of opposite charges: a negative boron ion and a positive silicon ion. In p-type semiconductor, because of thermal vibration, each neutral acceptor dopant atom (say boron) will grab an electron from a neutral silicon neighbor. Electrons are different, since they can be part of a neutral, un-ionized atom. Yes, each valence lattice vacancy (hole) is always a cation, since holes are always part of postive-charged atoms. ![]()
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