Free Electrons and Holes
Electrons that are available, for the flow of the current, above 0 Kelvin or above -273 degree Celcius is known as free electrons. Above 0 kelvin, these electrons gain energy and cross the energy band gap, leaving behind an empty space. This empty space is known as a hole. Holes are treated as +ve charges because there is a deficiency of -ve charge at that place.
What is Intrinsic Semiconductor ?
Intrinsic semiconductors are semiconductors that are pure i.e. it does not contain any impurity. Since it does not contain any impurity, the number of free electrons and the number of holes are equal. It is also known as an i-type semiconductor. The number of free electrons and the number of holes depends on the property of the material and does not depend on the doping.
For intrinsic semiconductors
n = p
where, n=number of electron, m=number of holes.
On the basis of electrical conductivity, materials are classified as:
- Conductors: Good conductors of electricity
- Insulators: Bad conductors of electricity
- Semiconductors: These materials have conductivity levels between those of conductors and insulators.
On the basis of the amount of doping, semiconductors are Classified as:
- Intrinsic Semiconductors
- Extrinsic Semiconductors
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