Doping:
The conductivity of silicon and germenium can be drastically increased by the controlled addition of impurities to the intrinsic (pure) semiconductor material. This process, called doping, increases the number of current carriers (electrons or holes).
N Type Semiconductor:
To increase the number of conduction band electrons , pentavalent impurity atoms like arsenic (As), phosphorus (P), bismith(Bi) and antimony (Sb) are added.
Each pentavalent atom leaves an extra free conduction electron after combining with the silicon atom forming covalent bond.As pentavalent atom gives an electron so called donar atom.
The number of conduction electrons can be controled by the impurities ato added to silicon.
Most of current carriers are electron,silicon doped with pentavalent atoms is an n-type semiconductor material.The electrons are called majority carriers.There are also some holes when electrons are paired when thermally processed.These holes are called minority carriers.
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1 comments:
It's funny that somehow, we always get taught about semiconductor doping without learning much about who stated the process. Who was the first one to figure out that adding impurities to the metal increased its conductivity?
I would like to know this, just for the sake of trivia. However, in the long run, all we need to know is the process behind the creation of the materials that are used to build the devices that are the backbone of most industries nowadays.
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