Asked by | 26th Feb, 2010, 03:30: PM
A P-type semiconductor (P for Positive) is obtained by carrying out a process of doping, that is adding a certain type of atoms to the semiconductor in order to increase the number of free charge carriers(in this case positive).
The purpose of P-type doping is to create an abundance of holes. In the case of silicon, a trivalent atom is substituted into the crystal lattice. The result is that one electron is missing from one of the four covalent bonds normal for the silicon lattice.Thus the dopant atom can accept an electron from a neighboring atom's covalent bond to complete the fourth bond. This is why such dopants are called acceptors. The dopant atom accepts an electron, causing the loss of half of one bond from the neighboring atom and resulting in the formation of a "hole". Each hole is associated with a nearby negatively-charged dopant ion, and the semiconductor remains electrically neutral as a whole.
Hope this helps.
Answered by | 27th Feb, 2010, 11:27: AM
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