EL Engg/Semiconductor Engineering/Level-1//Paper-01

1. In intrinsic semiconductors, number of electrons __________ number of holes. 

(a) Equal (b) Greater than (c) Less than (d) Can not define

Ans: (c) Less than

2. Fermi energy level for intrinsic semiconductors lies

(a) At middle of the band gap (b) Close to conduction band
(c) Close to valence band (d) None

Ans:(c) Close to valence band

3. Flow of electrons is affected by the following


(a) Thermal vibrations (b) Impurity atoms (c) Crystal defects (d) all

Ans: (d) all

4. Fermi level for extrinsic semiconductor depends on 

(a) Donor element (b) Impurity concentration (c) Temperature (d) All

Ans:(d) All

5. Fermi energy level for n-type extrinsic semiconductors lies 

(a) At middle of the band gap (b) Close to conduction band 

(c) Close to valence band (d) None

Ans: (b) Close to conduction band 

_______________________________SOLUTION___________________________________

5. Ans: (b) Close to conduction band.
The Fermi level lies in the middle of the forbidden gap.
Fermi level lies near valence band in P type and near conduction band in N type