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Question
Two crystals C1 and C2, made of pure silicon, are doped with arsenic and aluminium respectively.
Why is doping of intrinsic semiconductors necessary?
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Solution
Doping is necessary to increase the conductivity of semiconductors at normal temperatures.
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RELATED QUESTIONS
In an intrinsic semiconductor the energy gap Egis 1.2 eV. Its hole mobility is much smaller than electron mobility and independent of temperature. What is the ratio between conductivity at 600K and that at 300K? Assume that the temperature dependence of intrinsic carrier concentration niis given by
`"n"_"i" = "n"_0 exp(- "E"_"g"/(2"k"_"BT"))`
where n0 is a constant.
In a semiconductor, the number of holes and number of free electrons are represented as 'nh' and 'ne' respectively. Which one of the following statements is TRUE for the semiconductor?
In a pure or intrinsic semiconductor, valence band holes and conduction-band electrons are always ______.
Explain the following term:
Intrinsic semiconductor
Hole is ______.
What is meant by doping of an intrinsic semiconductor?
Name the two types of atoms used for doping of Ge/Si.
A pure semiconductor has equal electron and hole concentration of 1016 m-3. Doping by indium increases nh to 5 × 1022 m-3. Then, the value of ne in the doped semiconductor is ______.
Answer the following giving reasons:
Impurities are added to intrinsic semiconductors.
- Assertion (A): The resistance of an intrinsic semiconductor decreases with an increase in its temperature.
- Reason (R): The number of conduction electrons as well as hole increase in an intrinsic semiconductor with the rise in its temperature.
