An intrinsic semiconductor has some holes in it at room temperature. What causes these holes?

Hotel Aditya has 10 single AC rooms, 5 double AC rooms and 18 non AC rooms. The fixed monthly rent of hotel is 150,000. The per day maintenance cost is Rs. 100 for double AC room, Rs. 75 for single AC room and Rs. 40 for non AC room. The per day charges are Rs. 600 for double AC room, Rs. 400 for single AC room and Rs. 250 for non AC room. In April 2003, the occupancy rate of non AC room was 50%, 70% of single AC room and 40% of double AC rooms. Find the profit/loss % for that particular month.

A

10.33% (profit)

B

10.33% (loss)

C

5.67% (loss)

D

5.67% (profit)

E

No profit, no loss

A particular intrinsic semiconductor has a resistivity of 50 (ohm-cm) at T = 300 K and 5 (ohm-cm) at T = 330 K. If change in mobility with temperature is neglected, the bandgap energy of the semiconductor is

A

1.9 eV

B

1.3 eV

C

2.6 eV

D

0.64 eV

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

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

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

The effective density of states at the conduction band edge of Ge is 1.04 × 10¹⁹ cm^-3 at room temperature (300 K). Ge has an optical band gap of 0.66 eV. The intrinsic carrier concentration (in cm^-3) in Ge at room temperature (300 K) is approximately

A

3 × 10¹⁰

B

3 × 10¹³

C

3 × 10¹⁶

D

6 × 10¹⁶

At room temperature, an intrinsic semiconductor has ___________

A

Many holes only

B

A few free electrons and holes

C

Many free electrons only

D

No holes or free electrons

At room temperature an intrinsic semiconductor has

A

a few free electrons and holes

B

many holes

C

many free electrons

D

No holes

E

None of the above

The number of free electrons and holes in intrinsic semiconductor increases when the temperature

A

Decreases

B

Increases

C

Stays the same

D

0^oC

E

None of the above

For an intrinsic semiconductor, $$m_e^ * $$ and $$m_h^ * $$ are respectively, the effective masses of electrons and holes near the corresponding band edges. At a finite temperature, the position of the Fermi level

A

depends on $$m_e^ * $$ but not on $$m_h^ * $$

B

depends on $$m_h^ * $$ but not on $$m_e^ * $$

C

depends on both $$m_e^ * $$ and $$m_h^ * $$

D

depends neither on $$m_e^ * $$ nor on $$m_h^ * $$

At room temperature the current in an intrinsic semiconductor is due to

A

Holes

B

Electrons

C

Ions

D

Holes and electrons

An intrinsic semiconductor has some holes in it at room temperature. What causes these holes?

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