Extrinsic Semiconductor

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Extrinsic Semiconductor: Overview

This topic consists of various concepts like Extrinsic Semiconductor,Doping and Dopant,Doping, etc.

Important Questions on Extrinsic Semiconductor

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An intrinsic semiconductor has 5×1028 atoms and carrier concentration 1.5×1016 m-3. If it is doped by a pentavalent impurity in the ratio 1:106, then calculate the number density of holes as charge carriers.

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An intrinsic semiconductor has 5×1028 atoms and the carrier concentration 1.5×1016 m-3. If it is doped by a pentavalent impurity in the ratio 1:106, then calculate number density of holes as charge carriers.

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In a p-type semiconductor, which of the following statement is true?

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An N-type silicon sample of width 4×10-3 m thickness and length 6×10-2 m carries a current of 4.8 mA when the voltage is applied across the length of the sample. What is the current density? If the free electron density is 1022 m-3, then find how much time it takes for the electrons to travel the full length of the sample.

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For a pure Si crystal has 5×1028 atom $\mathrm{m}^{-3}$. It is doped by 1 PPM concentration of pentavalent As. Calculate the number of electron & holes.
(Given that ni=1.5×1016 m-3 )

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In a pure semiconductor crystal of Si, if antimony is added then what type of extrinsic semiconductor is obtained. Draw the energy band diagram of this extrinsic semiconductor so formed.

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When an intrinsic semiconductor such as Si is doped with a small amount of a trivalent impurity like boron

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The intrinsic carrier concentration in silicon at T=300 K is known to be ni=1.5×1016 m-3. A sample of silicon is doped with 5×1022 m-3 arsenic (a group V element). Under these circumstances the concentrations of electrons (n) and holes (p) in the sample are

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Intrinsic carrier concentration of a silicon sample at 300 K is 1.5×1016 m-3. After doping, the number of majority carriers is 2.25×1020 m-3. The minority carrier density is

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The base region of a silicon n-p-n transistor is obtained by doping Si with either

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What are minority current carriers in Extrinsic semiconductor.

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

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In n-type semiconductor, Silicon is doped with

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What is type of majority charge carriers present in p-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