CHAPTER-11, SEMICONDUCTOR

1. In which of the following the width of the forbidden band is, small

 
 
 
 

2. There is no hole current in good conductors because

 
 
 
 

3. Potential barrier of Si at 30°C is 0.7 eV. Which of the following can represent the potential barrier of Si at 100°C ?

 
 
 
 

4. What should be the order of number density of donor atoms to obtain an n semiconductor of conductivity 5 S cm-1. The mobility of electrons is 4000 cm2/Vs and the number density of holes is negligible

 
 
 
 

5. The number of electrons in the valence shell of the semiconductors is

 
 
 
 

6. In a semiconductor the forbidden energy gap is of the order of

 
 
 
 

7. Generally the number of electrons in the valence shell of good conductors is

 
 
 
 

8. The number density of free electrons in the semiconductor is 1018 m-3. It is doped with a pentavalent impurity atoms of number density 1024 m-3. The number density of free electrons m-3 increases by a factor of

 
 
 
 

9. A piece of copper and germanium are cooled from room temperature to 100 K. What happens to their resistivities ?

 
 
 
 

10. A solid having uppermost energy band partially filled with electrons is called

 
 
 
 

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