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With which one of the following elements silicon should be doped so as to give p-type of semiconductor ?
A
Selenium
B
Boron
C
Germanium
D
Arsenic
Detailed Solution
Silicon belongs to group 14 and has four valence electrons, each forming a covalent bond with a neighbouring silicon atom.
If silicon is doped with any element of group 13 (B, Al, Ga etc.) of the periodic table, a p-type semiconductor is obtained.
A group 13 atom such as boron has only three valence electrons, so it can form only three bonds; the fourth bond lacks an electron and a positive hole is created.
These holes move through the crystal and conduct electricity, hence the name p-type (positive).
Arsenic (group 15) has one extra electron and gives an n-type semiconductor; selenium (group 16) also supplies extra electrons.
Germanium is a group 14 element like silicon and creates neither holes nor extra electrons.
So silicon should be doped with boron.
If silicon is doped with any element of group 13 (B, Al, Ga etc.) of the periodic table, a p-type semiconductor is obtained.
A group 13 atom such as boron has only three valence electrons, so it can form only three bonds; the fourth bond lacks an electron and a positive hole is created.
These holes move through the crystal and conduct electricity, hence the name p-type (positive).
Arsenic (group 15) has one extra electron and gives an n-type semiconductor; selenium (group 16) also supplies extra electrons.
Germanium is a group 14 element like silicon and creates neither holes nor extra electrons.
So silicon should be doped with boron.