Density of Charge Carriers
Category : JEE Main & Advanced
Due to thermal collisions, an electron can take up or release energy. Thus, occasionally a valence electron takes up energy and the bond is broken. The electron goes to the conduction band and a hole is created. And occasionally, an electron from the conduction band loses some energy, comes to the valence band and fills up a hole. Thus, new electron-hole pairs are formed as well as old electron-hole disappear. A steady-state situation is reached and the number of electron-hole pairs takes a nearly constant value. For silicon at room temperature (300 K), the number of these pairs is about \[7\times {{10}^{15}}\,\,{{m}^{3}}\]. For germanium, this number is about \[6\times {{10}^{19}}/\,\,{{m}^{3}}\].
Densities of charge carriers
| Material | Type | Density of conduction electrons (m- 3) | Density of holes (m-3) |
| Copper | Conductor | \[9\times {{10}^{28}}\] | 0 |
| Silicon | Intrinsic semiconductor | \[7\times {{10}^{75}}\] | \[7\times {{10}^{15}}\] |
| Silicon doped with phosphorus (1 part in \[{{10}^{6}}\]) | N-type semiconductor | \[5\times {{10}^{22}}\] | \[1\times {{10}^{9}}\] |
| Silicon doped with aluminium (1 part in \[{{10}^{6}}\]) | P-type semiconductor | \[1\times {{10}^{9}}\] | \[5\times {{10}^{22}}\] |
You need to login to perform this action.
You will be redirected in
3 sec
