A semiconductor has generally ___________ valence electrons.

A semiconductor has generally . . . . . . . . valence electrons.

A

3

B

4

C

6

D

2

An intrinsic semiconductor with mass of a hole m_h, and mass of an electron m_e is at a finite temperature T. If the top of the valence band energy is E_v and the bottom of the conduction band energy is E_c, the Fermi energy of the semiconductor is

A

$${E_F} = \left( {\frac{{{E_v} + {E_c}}}{2}} \right) - \frac{3}{4}{k_B}T\ln \left( {\frac{{{m_h}}}{{{m_e}}}} \right)$$

B

$${E_F} = \left( {\frac{{{k_B}T}}{2}} \right) + \frac{3}{4}\left( {{E_v} + {E_c}} \right)\ln \left( {\frac{{{m_h}}}{{{m_e}}}} \right)$$

C

$${E_F} = \left( {\frac{{{E_v} + {E_c}}}{2}} \right) + \frac{3}{4}{k_B}T\ln \left( {\frac{{{m_h}}}{{{m_e}}}} \right)$$

D

$${E_F} = \left( {\frac{{{k_B}T}}{2}} \right) - \frac{3}{4}\left( {{E_v} + {E_c}} \right)\ln \left( {\frac{{{m_h}}}{{{m_e}}}} \right)$$

If the number of electrons (majority carrier) in a semiconductor is 5 X 1020 m-3 and μe is 0.135 mho, find the resistivity of the semiconductor.

A

0.0926 Ωm

B

0.0945 Ωm

C

0.0912 Ωm

D

0.0978 Ωm

The process of excitation of an electron from valence band to conduction band leaves an empty hole in the valence band and is called as ____________

A

Detection

B

Absorption

C

Degeneration of an electron-hole pair

D

Regeneration of an electron-hole pair

In a semiconductor it is observed that three-quarters of the current is carried by electrons and one quarters by holes. If the drift speed is three times that of the holes, what is the ratio of electrons to holes?

A

1 : 1

B

1 : 2

C

2 : 1

D

4 : 1

A pentavalent impurity has ___________ Valence electrons

A

3

B

5

C

4

D

6

Carbonium ions are the intermediates in which the positive charge is carried by the carbon atom with ___________ electrons in the valence shell.

A

6

B

5

C

4

D

3

A trivalent impurity has valence electrons

A

4

B

5

C

6

D

3

Which of the following elements has three valence electrons?

A

Al

B

Ag

C

Au

D

Ca

Gallium has ______ valence electrons.

A

two

B

three

C

four

D

five

A semiconductor has generally ___________ valence electrons.

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