- 1(current)
Q. No.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. | \(\mathrm{p}\text-\)type semiconductor |
| 2. | insulator |
| 3. | metal |
| 4. | \(\mathrm{n}\text-\)type semiconductor |
Subtopic: Â Energy Band theory |
 76%
Level 2: 60%+
AIPMT - 2007
Hints
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 \(10~\text{eV}\) 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: Â Energy Band theory |
 81%
Level 1: 80%+
AIPMT - 2005
Hints
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: Â Energy Band theory |
 71%
Level 2: 60%+
Hints
A \(\mathrm{p\text-n}\) photodiode is fabricated from a semiconductor with a band gap of \(2.5~\text{eV}.\) It can detect a signal of wavelength:
1. \(6000~\mathring{A}\)
2. \(4000~\text{nm}\)
3. \(6000~\text{nm}\)
4. \(4000~\mathring{A}\)
1. \(6000~\mathring{A}\)
2. \(4000~\text{nm}\)
3. \(6000~\text{nm}\)
4. \(4000~\mathring{A}\)
Subtopic: Â Energy Band theory |
 64%
Level 2: 60%+
AIPMT - 2009
Hints
\(\mathrm{C}\) and \(\mathrm{Si}\) both have the same lattice structure, having \(4\) bonding electrons in each. However, \(\mathrm{C}\) is an insulator whereas \(\mathrm{Si}\) is an intrinsic semiconductor. This is because:
| 1. | in the case of \(\mathrm{C},\) the valence band is not completely filled at absolute zero temperature. |
| 2. | in the case of \(\mathrm{C},\) the conduction band is partly filled even at absolute zero temperature. |
| 3. | the four bonding electrons in the case of \(\mathrm{C}\) lie in the second orbit, whereas in the case of \(\mathrm{Si},\) they lie in the third. |
| 4. | the four bonding electrons in the case of \(\mathrm{C}\) lie in the third orbit, whereas for \(\mathrm{Si},\) they lie in the fourth orbit. |
Subtopic: Â Energy Band theory |
 72%
Level 2: 60%+
NEET - 2012
Hints
- 1(current)
Q. No.
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