Looking for classes? Ksquare Career Institute, Bengaluru →
Semiconductors and Doping
Concepts tested here
- p-type and n-type doping
All Questions
2008 AIPMT 1 question
-
With which one of the following elements silicon should be doped so as to give p-type of semiconductor ?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.