Electronic Devices Question 212
Question: A silicon speciman is made into a P-type semi-conductor by dopping, on an average, one Indium atom per $ 5\times 10^{7} $ silicon atoms. If the number density of atoms in the silicon specimen is $ 5\times 10^{28}\text{atoms}/m^{3} $ then the number of acceptor atoms in silicon per cubic centimetre will be
[MP PMT 1993, 2003]
Options:
A) $ 2.5\times 10^{30}atoms/cm^{3} $
B) $ 1.0\times 10^{13}atoms/cm^{3} $
C) $ 1.0\times 10^{15}atoms/cm^{3} $
D) $ 2.5\times 10^{36}atoms/cm^{3} $
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Answer:
Correct Answer: C
Solution:
Number density of atoms in silicon specimen = ${5 x 10^28 atom/m^3}$ = ${5 x 1022 atom/cm^3}$ Since one atom of indium is doped in 5 x 107 Si atom.
So number of indium atoms doped per cm3 of silicon.
$ n=\frac{5\times 10^{22}} {5\times 10^{7}} = 1\times 10^{15}atom/cm^{3}.$
BETA
