In an intrinsic semiconductor, the concentration of electrons
(ni) and holes
(pi) are equal and given by:
ni=pi=6×1015m−3.When the semiconductor is doped with an impurity, the electron concentration increases to
4×1022m−3, which is denoted by
n. The product of the electron concentration (
n ) and the hole concentration (
p ) in a semiconductor at thermal equilibrium is given by:
nâ‹…p=ni2.To find the hole concentration
(p) in the doped semiconductor, use the above relationship:
Calculate
ni2 :
ni2=(6×1015m−3)2=36×1030m−6.Using the relation
nâ‹…p=ni2, solve for
p :
p=‌=‌| 36×1030m−6 |
| 4×1022m−3 |
.Calculate
p :
p=‌×1030−22m−3=9×108m−3.Therefore, the concentration of holes in the doped semiconductor is
9×108m−3, which corresponds to Option C.
