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1. Name different types of energy bands?
Different energy bands are
- Conduction band (C)
- Valence band (V)
2. Define a hole?
A place vocated by an electron is called a hole. It is associated with a positive charge.
3. Define an intrinsic semiconductor?
A pure semiconductor material, is called an intrinsic semiconductor.
4. Define an extrinsic semiconductor?
A semiconductor material made deliberately impure, is called an extrinsic semiconductor.
5. Which materials are commonly used as semiconductor?
Silicon and germanium are commonly used as semiconductors.
6. Which of the upper two materials has less energy gap?
Energy gap has value 0.72 ev for germanium and 1.12 ev for silicon.
7. Describe an n-type semiconductor?
An n-type Ge is obtained by adding a small quantity (one millionth part) of a pentavalent impurity to its crystal.
8. Name the pentavalent impurities which make Ge n-type?
The pentavalent impurities are
- Phosphorus (15)
- Arsenic (33)
- Antimony (51)
- Bismuth (83)
9. Describe a P-type semiconductor?
A P-type is obtained by adding a small quantity (one millionth part) of a trivalent impurity to its crystal.
10. Name the trivalent impurities which make P-type?
The trivalent impurities are
- Boron (5)
- Aluminium (13)
- Gallium (31)
- Indium (49)
- Thalium (81)
11. What is doping?
The process of adding a suitable impurity to pure semiconductor, deliberately, is called doping.
12. What is a depletion layer?
The region arround a PN- junction diode where there is no charge carrier.
13. What is junction potential barrier?
The potential difference between junction ends of the two types of semiconductors due to which no charge carrier flow across the junction, is called potential barrier.
14. What is biasing of a junction?
Applying an external potential difference more than potential barrier on the faces of the junction, is called biasing of a junction.
15. Give names of the two types of the biasing?
The two types of biasing are
- Forward biasing
- Reverse biasing
16. How does the bias effect the thickness of the depletion layer?
- Forword bias decreases the thickness of depletion layer.
- Reverse bias increases the thickness of depletion layer.
17. How does the bias effect the junction resistance?
- The forword bias makes junction resistance less
- The reverse bias makes junction resistance more.