The Intrinsic and Extrinsic semiconductors are distinguished from each other considering various factors such as doping or the addition of the impurity, density of electrons and holes in the semiconductor material, electrical conductivity, and its dependency on various other factors.
The difference between the two types of semiconductor is given below in detail.
| BASIS OF DIFFERENCE | INTRINSIC SEMICONDUCTOR | EXTRINSIC SEMICONDUCTOR |
|---|---|---|
| Doping of impurity | Doping or addition of impurity does not take place in intrinsic semiconductor. | A small amount of impurity is dopped in a pure semiconductor for preparing extrinsic semiconductor. |
| Density of electrons and holes | The number of free electrons in the conduction band is equal to the number of holes in the valence band. | The number of electrons and holes are not equal. |
| Electrical conductivity | Electrical conductivity is low. | Electrical conductivity is high |
| Dependency of electrical conductivity | Electrical conductivity is a function of temperature alone. | Electrical conductivity depends on temperature as well as on the amount of impurity doping in the pure semiconductor. |
| Example | Crystalline form of pure Silicon and Germanium. | Impurity like As, Sb, P, In, Bi, Al etc. are dopped with Germanium and Silicon atom. |
Intrinsic Semiconductor is a pure form of the semiconductor as here no addition of impurity takes place. An example of intrinsic semiconductors is Silicon (Si) and Germanium (Ge).
On the other hand, when a small quantity of Tetravalent or Pentavalent impurity like Arsenic (As), Aluminium (Al), Phosphorus (P), Galium (Ga), Indium (In), Antimony (Sb) etc. is added to pure semiconductor, an Extrinsic Semiconductor is obtained.
Difference Between Intrinsic and Extrinsic Semiconductor
- In an intrinsic semiconductor, the addition of impurity with a pure semiconductor does not take place, whereas the extrinsic semiconductor is formed by the dopping of impurity in a pure semiconductor.
- The density of electrons and holes in the intrinsic semiconductor is same, i.e. the number of free electrons present in the conduction band is equal to the number of holes in the valence band. But in the case of extrinsic semiconductors, the number of electrons and holes are not equal. In a p-type semiconductor, the holes are in excess and n-type semiconductor the number of electrons is greater than the number of holes.
- The electrical conductivity of an intrinsic semiconductor is low, whereas in extrinsic semiconductor the electrical conductivity is high.
- The impurity like arsenic, antimony, phosphorus, aluminium indium, etc. is added to the pure form of silicon and germanium to form an extrinsic semiconductor. The pure form of silicon and germanium crystal is used in an intrinsic semiconductor.
- Electrical conductivity in an intrinsic semiconductor is a function of temperature alone, but in extrinsic semiconductor the electrical conductivity depends upon the temperature and the amount of impurity doping in the pure semiconductor.
In this way, intrinsic semiconductors are different from extrinsic semiconductors.
what kind of elements are doped with the silicon and Germenium in extrinsic semiconductor?
Pentavalent and trivalent element can doped🙂