Extrinsic Semiconductors

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Extrinsic Semiconductors: Overview

This topic covers concepts, such as, N-type Semiconductor, Some Important Facts about n-Type Semiconductor, Energy Bands Diagram of N-type Semiconductor & Energy Bands Diagram of P-type Semiconductor etc.

Important Questions on Extrinsic Semiconductors

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The diagram below is showing:

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

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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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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

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Electric current in extrinsic semiconductor in respect of mobility is expressed as

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Electric current in extrinsic semiconductor is

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In an n-type silicon, which of the following statement is true:

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A N-type semiconductor is:

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

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These are the minority charge carriers in n-type semiconductors.

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Identify the minority charge carriers in p-type semiconductors

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In an n-type silicon, which of the following statement is true:

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

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In the above figure, if the Ge in the circled position is replaced by the Ga, then the resultant forms which type of semiconductor?

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Which of the following is true regarding P-type semiconductor ?

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1016 phosphorus atoms  cm-3 and 2×1016 boron atoms cm-3 are doped in a sample of silicon. If all the dopants are fully ionised, the material is