- 1(current)
Q. No.The acceptor level of a p-type semiconductor is \(6\) eV. The maximum wavelength of light which can create a hole would be : Given \(h c=1242\) eV-nm.
1. \(407\) nm
2. \(207\) nm
3. \(103.5\) nm
4. \(414\) nm
Subtopic: Â Energy Band theory |
 91%
Level 1: 80%+
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The energy band gap of semiconducting material to produce violet (wavelength \(=4000~\mathring{A}\)) LED is (nearly):
1. \(3~\text{eV}\)
2. \(5~\text{eV}\)
3. \(1~\text{eV}\)
4. \(7~\text{eV}\)
1. \(3~\text{eV}\)
2. \(5~\text{eV}\)
3. \(1~\text{eV}\)
4. \(7~\text{eV}\)
Subtopic: Â Energy Band theory |
 86%
Level 1: 80%+
Hints
An LED is constructed from \(\mathrm{Ga\text-As\text-P}\) semiconducting material with an energy gap of \(1.9~\text{eV}.\) What is the wavelength of the emitted light and what colour does it correspond to?
(take \(h=6.63\times10^{-34}~\text{J-s}\) and \(c=3\times10^8~\text{m/s}\))
| 1. | \(1046~\text{nm}\) and red colour |
| 2. | \(654~\text{nm}\) and orange colour |
| 3. | \(1046~\text{nm}\) and blue colour |
| 4. | \(654~\text{nm}\) and red colour |
Subtopic: Â Energy Band theory |
Level 3: 35%-60%
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Hints
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For extrinsic semiconductors, when doping level is increased:
| 1. | Fermi-level of \(p\)-type semiconductors will go upward and Fermi-level of \(n\)-type semiconductors will go downward. |
| 2. | Fermi-level of \(p\)-type semiconductors will go downward and Fermi-level of \(n\)-type semiconductors will go upward. |
| 3. | Fermi-level of both \(p\)-type and \(n\)-type semiconductors will go upward for \(T>T_F\) K and downward for \(T<T_F\) K, where \(T_F\) is Fermi temperature. |
| 4. | Fermi-level of \(p\) and \(n\)-type semiconductors will not be affected. |
Subtopic: Â Energy Band theory |
 60%
Level 2: 60%+
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- 1(current)
Q. No.
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