What do we mean by \"doping\" semiconductors? Adding atoms above or below the cr
ID: 1469820 • Letter: W
Question
What do we mean by "doping" semiconductors?
Adding atoms above or below the crystal atom on the periodic table.
Adding atoms with one more or one fewer valence electrons than the crystal atom.
Charging the semiconductor to add or remove electrons.
Irradiating the semiconductor to remove electrons.
a.Adding atoms above or below the crystal atom on the periodic table.
b.Adding atoms with one more or one fewer valence electrons than the crystal atom.
c.Charging the semiconductor to add or remove electrons.
d.Irradiating the semiconductor to remove electrons.
Explanation / Answer
The addition of a small percentage of foreign atoms in the regular crystal lattice of silicon or germanium produces dramatic changes in their electrical properties, producing n-type and p-type semiconductors.
The application of band theory to n-type and p-type semiconductors shows that extra levels have been added by the impurities. In n-type material there are electron energy levels near the top of the band gap so that they can be easily excited into the conduction band. In p-type material, extra holes in the band gap allow excitation of valence band electrons, leaving mobile holes in the valence band.
Doping means the introduction of impurities into a semiconductor crystal to the defined modification of conductivity. Two of the most important materials silicon can be doped with, are boron (3 valence electrons = 3-valent) and phosphorus (5 valence electrons = 5-valent)
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