Electronic DevicesSemiconductors (NEET (NTA)National Eligibility cum Entrance Test (Medical) Physics): Questions 19  23 of 23
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Question number: 19
» Electronic Devices » Semiconductors
Question
The energy gap for diamond is nearly
Choices
Choice (4)  Response  

a.  2 eV 

b.  1 eV 

c.  6 eV 

d.  4 eV 

Question number: 20
» Electronic Devices » Semiconductors
Question
The intrinsic semiconductor becomes an insulator at
Choices
Choice (4)  Response  

a.  100°C 

b.  0 K 

c.  0°C 

d.  300 K 

Passage
Doping changes the Fermi energy of a semiconductor. Consider silicon, with a gap of 1.11 eV between the top of the valence bond and the bottom of the conduction band. At 300K the Fermi level of the pure material is nearly at the midpoint of the gap. Suppose that silicon is doped with donor atoms, each of which has a state 0.15 eV below the bottom of the silicon conduction band, and suppose further that doping raises the Fermi level to 0.11 eV below the bottom of that band.
Question number: 21 (1 of 3 Based on Passage) Show Passage
» Electronic Devices » Semiconductors
Question
Calculate the probability that a donor state in the doped material is occupied?
Choices
Choice (4)  Response  

a.  0.008 

b.  0.824 

c.  8.2 

d.  0.08 

Question number: 22 (2 of 3 Based on Passage) Show Passage
» Electronic Devices » Semiconductors
Question
For pure silicon, calculate the probability that a state at the bottom of the silicon conduction band is occupied? (e ^{21.46} = 20.89 ⨯ 10 ^{8})
Choices
Choice (4)  Response  

a.  4 ⨯ 10 ^{10} 

b.  4.79 ⨯ 10 ^{10 } 

c.  5.20 ⨯ 10 ^{12} 

d.  3.42 ⨯ 10 ^{11} 

Question number: 23 (3 of 3 Based on Passage) Show Passage
» Electronic Devices » Semiconductors
Question
For doped silicon, calculate the probability that a state at the bottom of the silicon conduction band is occupied? (e ^{4.254} = 70.38)
Choices
Choice (4)  Response  

a.  10.5 ⨯ 10 ^{2 } 

b.  1.40 ⨯ 10 ^{2} 

c.  14 ⨯ 10 ^{2} 

d.  5.20 ⨯ 10 ^{2} 
