In the energy band diagram of a material shown below, the open circles and filled circles denote holes and electrons respectively. The material is a/an: 


     

1. p-type semiconductor
2. insulator
3. metal
4. n-type semiconductor

Subtopic:  Energy Band theory |
 75%
From NCERT
AIPMT - 2007
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In a good conductor, the energy gap between the conduction band and the valence band is
1. Infinite
2. Wide
3. Narrow
4. Zero

Subtopic:  Energy Band theory |
 78%
From NCERT
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Identify the incorrect statement from the following:

1. The resistivity of a semiconductor increases with an increase in temperature.
2. Substances with an energy gap of the order of 10 eV are insulators.
3. In conductors, the valence and conduction bands may overlap.
4. The conductivity of a semiconductor increases with an increase in temperature.
Subtopic:  Energy Band theory |
 78%
From NCERT
AIPMT - 2005
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Carbon, Silicon, and Germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy gaps represented by \(\left(E_g\right)_C,(E_g)_{Si}~\text{and}~(E_g)_{Ge}\) respectively. Which one of the following relationships is true in their case?

1. \(\left(E_g\right)_C<\left(E_g\right)_{G e} \) 2. \(\left(E_g\right)_C>\left(E_g\right)_{S i} \)
3. \(\left(E_g\right)_C=\left(E_g\right)_{S i} \) 4. \(\left(E_g\right)_C<\left(E_g\right)_{S i}\)
Subtopic:  Energy Band theory |
 71%
From NCERT
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The energy band diagrams for semiconductor samples of silicon are as shown. We can assert that:

          

1. sample X is undoped while samples Y and Z have been doped with a third group and a fifth group impurity respectively.
2. sample X is undoped while both samples Y and Z have been doped with a fifth group impurity.
3. sample X has been doped with equal amounts of third and fifth group impurities while samples Y and Z are undoped.
4. sample X is undoped while samples Y and Z have been doped with a fifth group and a third group impurity respectively.
Subtopic:  Energy Band theory |
 68%
From NCERT
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In semiconductors at room temperature:

1. The valence band is completely filled and the conduction band is partially filled.
2. The valence band is completely filled.
3. The conduction band is completely empty.
4. The valence band is partially empty and the conduction band is partially filled.
Subtopic:  Energy Band theory |
 70%
From NCERT
AIPMT - 2004
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p-n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. It can detect a signal of wavelength:
1. 6000 Å
2. 4000 nm
3. 6000 nm
4. 4000 Å
 
Subtopic:  Energy Band theory |
 62%
From NCERT
AIPMT - 2009
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How much is the forbidden gap in the energy bands of germanium at room temperature? 
1. 1.1 eV                           

2. 0.1 eV

3. 0.67 eV                         

4. 6.7 eV 

Subtopic:  Energy Band theory |
 60%
From NCERT
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Which of the energy band diagrams shown in the figure corresponds to that of a semiconductor?

1. 2.
3. 4.
Subtopic:  Energy Band theory |
 56%
From NCERT
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A semiconductor is known to have an electron concentration of 8×1013 cm-3 and a hole concentration of 5×102 cm-3. The semiconductor is:

1.  n-type

2.  p-type

3.  intrinsic

4.  insulator

Subtopic:  Types of Semiconductors |
 88%
From NCERT
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