10 QA on Semiconductors | Learn Physics

10 Question-Answer on Semiconductors

1.       With the fall of temperature, the forbidden energy gap of a semiconductor

(a)    Increases

(b)   Decreases

(c)    Remains unchanged

(d)   Sometime increases and sometimes decreases

Ans: ( c)

2.       What is the resistivity of a pure semiconductor at absolute zero?

(a)    Zero

(b)   Infinity

(c)    Same as that of conductors at room temperature

(d)   Same as that of insulators at room temperatures

Ans: (b)

3.       What enables Ge behave as semiconductor even through all electrons in the valence bond form covalent bonds? It is due to small with of

(a)    Valence bond

(b)   Conduction band

(c)    Forbidden energy gap

(d)   None of above.

Ans: (c )

4.       An n-type and p-type silicon can be obtained by doping pure silicon with

(a)    Sodium and magnesium

(b)   Phosphorus and boron respectively

(c)    Boron and phosphorus respectively

(d)   Indium and sodium respectively.

Ans: (b)

5.       In a p type semiconductor, the acceptor valence band is

(a)    Close to the valence band of the host crystal

(b)   Close to conduction band of host crystal

(c)    Below the conduction band of the host crystal

(d)   Above the conduction band of te host crystal

Ans: ( a)

6.       In an N-type semiconductor, donor valence band is:

(a)    Above the conduction band of the host crystal

(b)   Close to the valence band of the host crystal

(c)    Close to the conduction band of the host crystal

(d)   Below the valence band of the host crystal.

Ans: (c)

7.       An N-type semiconductor is

(a)    Negatively charged

(b)   Positively charged

(c)    Neutral

(d)   Negatively or positively charged depending upon the amount of impurity,

Ans: (c)

8.       In a good conductor, the engry levels in a valence band:

(a)    Are partially filled only

(b)   Overlap with conduction band only

(c)    Both 1 and 2 are correct

(d)   Neither 1 nor 2 is correct.

Ans: ( b)

9.       Resistivity a semiconductor depends on

(a)    Shape of semiconductor

(b)   Atomic nature of semiconductor

(c)    Length of semiconductor

(d)   Shape and atomic nature of semiconductor.

Ans: (b)

10.       When arsenic is added as an impurity to silicon, the resulting material is:

(a)    P-type semiconductor

(b)   N-type semiconductor

(c)    P-type conductor

(d)   N-type conductor

Ans: (c)