18
MCQ (Single Correct Answer)
Schottky defect is observed in crystals when ............ .
A
some cations move from their lattice site to interstitial sites
B
equal number of cations and anions are missing from the lattice
C
some lattice sites are occupied by electrons
D
some impurity is present in the lattice
19
MCQ (Single Correct Answer)
Which of the following is true about the charge acquired by p - type semiconductors?
A
Positive
B
Neutral
C
Negative
D
Depends on concentration of $p$ impurity
20
MCQ (Single Correct Answer)
To get a n-type semiconductor from silicon, it should be doped with a substance with valency ............. .
A
2
B
1
C
3
D
5
21
MCQ (Single Correct Answer)
The total number of tetrahedral voids in the face centred unit cell is .......... .
A
6
B
8
C
10
D
12
22
MCQ (Single Correct Answer)
Which of the following point defects are shown by $\mathrm{AgBr}(\mathrm{s})$ crystals?
1. Schottky defect
2. Frenkel defect
3. Metal excess defect
4. Metal deficiency defect
A
1 and 2
B
3 and 4
C
1 and 3
D
2 and 4