
21Introduction to Nanosensors
majority carriers. Holes are termed the minority carriers. In a P-type semicon-
ductor, holes are majority carriers and electrons are minority carriers.
Thus, by deliberate incorporation of known amounts of phosphorous
or boron atoms in semiconductors, conductivities of resulting N-type and
P-type semiconductors can be varied within wide limits. However, both
N-type and P-type semiconductors are electrically neutral as a whole
because the number of electrons = number of positively charged donor ions
in an N-type semiconductor and the number of holes = number of negatively
charged acceptor ions i ...