- 1(current)
Q. No.Hole is:
| 1. | an anti-particle of electron. |
| 2. | a vacancy created when an electron leaves a covalent bond. |
| 3. | absence of free electrons. |
| 4. | an artificially created particle. |
Subtopic: Â Types of Semiconductors |
 89%
Level 1: 80%+
Hints
Let \(n_{p}\) and \(n_{e}\) be the number of holes and conduction electrons in an intrinsic semiconductor. Then:
1. \(n_{p}> n_{e}\)
2. \(n_{p}= n_{e}\)
3. \(n_{p}< n_{e}\)
4. \(n_{p}\neq n_{e}\)
Subtopic: Â Types of Semiconductors |
 84%
Level 1: 80%+
Hints
A \(\mathrm{p}\text-\)type of semiconductor is:
1. positively charged
2. negatively charged
3. uncharged
4. uncharged at \(0~\text{K}\) but charged at higher temperatures
Subtopic: Â Types of Semiconductors |
 60%
Level 2: 60%+
Hints
Which of the following is correct for \(\mathrm{n}\)-type semiconductors?
| 1. | electron is the majority carriers and trivalent atoms are dopants. |
| 2. | electrons are majority carriers and pentavalent atoms are dopants. |
| 3. | holes are majority carriers and pentavalent atoms are dopants. |
| 4. | holes are majority carriers and trivalent atoms are dopants. |
Subtopic: Â Types of Semiconductors |
 87%
Level 1: 80%+
Hints
In semiconductors, which of the following gives the law of mass action? (where symbols have their usual meanings.)
1. \(n_i=n_e=n_h\)
2. \(n_i^2=n_en_h\)
3. \(n_h>> n_e\)
4. \(n_h<<n_e\)
1. \(n_i=n_e=n_h\)
2. \(n_i^2=n_en_h\)
3. \(n_h>> n_e\)
4. \(n_h<<n_e\)
Subtopic: Â Types of Semiconductors |
 81%
Level 1: 80%+
Hints
When a \(\mathrm{p\text-}\)type semi-conductor is put in an electric field \(\vec{E}\) the electrons in the valence band, on average:
| 1. | flow in the direction of the \(\vec{E}\) and cause a current opposite to \(\vec{E}\) |
| 2. | flow opposite to \(\vec{E}\) and cause a current along \(\vec{E}\) |
| 3. | flow along \(\vec{E}\) and cause a current along \(\vec{E}\) |
| 4. | flow opposite to \(\vec{E}\) and cause a current opposite to \(\vec{E}\) |
Subtopic: Â Types of Semiconductors |
 64%
Level 2: 60%+
Hints
Pure Si at \(500~\text{K}\) has an equal number of electron \((n_e)\) and hole \((n_h)\) concentrations of \(1.5\times10^{16}~\text{m}^{-3}\). Doping by indium increases \(n_h\) to \(4.5\times10^{22}~\text{m}^{-3}\). The doped semiconductor is of:
| 1. | \(p\)-type with electron concentration \(n_e=5\times10^9~\text{m}^{-3}\). |
| 2. | \(n\)-type with electron concentration \(n_e=5\times10^{22}~\text{m}^{-3}\). |
| 3. | \(p\)-type with electron concentration \(n_e=2.5\times10^{10}~\text{m}^{-3}\). |
| 4. | \(n\)-type with electron concentration \(n_e=2.5\times10^{23}~\text{m}^{-3}\). |
Subtopic: Â Types of Semiconductors |
 77%
Level 2: 60%+
AIPMT - 2011
Hints
When an impurity is doped into an intrinsic semiconductor, the conductivity of the semiconductor:
1. increases
2. decreases
3. remains the same
4. becomes zero
Subtopic: Â Types of Semiconductors |
 84%
Level 1: 80%+
Hints
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Suppose a pure \(\mathrm{Si}\) crystal has \(5\times10^{28}~\text{atoms m}^{-3}.\) It is doped by a \(1~\text{ppm}\) concentration of pentavalent \(\mathrm{As}.\) The number of electrons and holes are, respectively:
(given: \(n_i=1.5\times10^{16}~\text{m}^{-3}\))
(given: \(n_i=1.5\times10^{16}~\text{m}^{-3}\))
| 1. | \(5\times10^{22}~\text{m}^{-3}, 4.5\times10^{9}~\text{m}^{-3}\) |
| 2. | \(4.5\times10^{9}~\text{m}^{-3}, 5\times 10^{22}~\text{m}^{-3}\) |
| 3. | \(5\times10^{22}~\text{m}^{-3}, 5\times10^{22}~\text{m}^{-3}\) |
| 4. | \(4.5\times10^{9}~\text{m}^{-3}, 4.5\times 10^{9}~\text{m}^{-3}\) |
Subtopic: Â Types of Semiconductors |
 62%
Level 2: 60%+
Hints
A \(\mathrm{p} \text-\)type extrinsic semiconductor is obtained when Germanium is doped with:
1. antimony
2. phosphorous
3. arsenic
4. boron
1. antimony
2. phosphorous
3. arsenic
4. boron
Subtopic: Â Types of Semiconductors |
 76%
Level 2: 60%+
NEET - 2023
Hints
- 1(current)
Q. No.
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