Semiconductor Doping - Intrinsic and Extrinsic Semiconductors

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Semiconductor Doping - Intrinsic and Extrinsic Semiconductors: Overview

This topic covers concepts, such as, Intrinsic Semiconductor, Electrical Conductivity of Intrinsic Semiconductor, Effect of Temperature on Intrinsic Charge Carrier Density & Energy Level Diagram of Intrinsic Semiconductor etc.

Important Questions on Semiconductor Doping - Intrinsic and Extrinsic Semiconductors

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Which of the following energy band diagram shows the N-type semiconductor

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What will happen if we increase temperature in an intrinsic semiconductor ?

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In an intrinsic semiconductor, Its carrier density increases with _____.

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In an intrinsic semiconductor, Its carrier density increases with temperature.

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An intrinsic semiconductor has the following properties:

1. Its electron concentration equals its hole concentration.

2. Its carrier density increases with temperature.

3. Its conductivity decreases with temperature.

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Fermi energy level for intrinsic semiconductors lies at _____ of the band gap.

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Fermi energy level for intrinsic semiconductors lies at middle of the band gap.

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Draw energy band diagram of p & n type semiconductors. Also write two differences between p and n type semiconductors. 

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Draw the energy band diagram when intrinsic semiconductor (Ge) is doped with impurity atoms of Antimony (Sb). Name the extrinsic semiconductor so obtained and majority charge carriers in it.

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No crystal is found to be prefect at room temperature. The defects present in the crystals can be stoichiometric or non-stoichiometric. Due to nonstoichiometric defects, the formula of the ionic compound is different from the ideal formula. For example, the ideal formula of ferrous oxide should be FeO but actually in one sample, it was found to be Fe0.93O. This is because the crystal may have some ferric ions in place of ferrous ions. These defects change the properties of the crystals. In some cases, defects are introduced to have crystals of desired properties as required in the field of electronics. Doping of elements of Group 14 with those of Group 13 or 15 is most common. In ionic compounds, usually impurities are introduced in which the cation has higher valency than the cation of the parent crystal, e.g., SrCl2 into NaCl.

Which one of the following doping will produce p-type semiconductor ?

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The hole density (ηh) and electron density (ne) in p-type semiconductors are related as

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Range of energy required by electron of valance band to move into hole is 0.01-0.05 eV. The accepter energy level lies

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In a pure semiconductor, electric current is due to_________.

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In a p–type semiconductor, the concentration of holes is2 × 1015 cm-3  The intrinsic carrier concentration is2 × 1010 cm-3 . The concentration of electrons will be.

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Assertion : An n-type semiconductor has a large number of electrons but still it is electrically neutral.

 Reason : An n-type semiconductor is obtained by doping an intrinsic semiconductor with a pentavalent impurity. 

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Which of the following energy band diagram shows the N-type semiconductor

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The energy gap between conduction band and valence band in n-type semiconductor is

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A semiconductor has equal electron and holes concentration of 6×108 m-3. On doping with certain impurity, electron concentration becomes 9×1012 m-3. Then the semiconductor is