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Question
Hole is ______.
Options
an anti-particle of electron.
a vacancy created when an electron leaves a covalent bond.
absence of free electrons.
an artifically created particle.
Solution
Hole is a vacancy created when an electron leaves a covalent bond.
Explanation:
Concept of holes in the semiconductor:
- When an electron is removed from a covalent bond, it leaves a vacancy behind. An electron from a neighbouring atom can move into this vacancy, leaving the neighbour with a vacancy. In this way, the vacancy formed is called a hole (or cotter) and can travel through the material and serve as an additional current carrier.
- A hole is considered a seat of positive charge, having a magnitude of charge equal to that of an electron.
- Holes act as a virtual charge, although there is no physical charge on them.
- The effective mass of a hole is more than an electron.
- The mobility of a hole is less than an electron.
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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.
Let np and ne be the numbers of holes and conduction electrons in an extrinsic semiconductor.
Answer in detail.
Distinguish between intrinsic semiconductors and extrinsic semiconductors.
Let nh and ne be the number of holes and conduction electrons respectively in a semiconductor. Then ______.
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?
An intrinsic semiconductor has a resistivity of 0.50 Ω m at room temperature. Find the intrinsic carrier concentration if the mobilities of electrons and holes are 0.39 m2V-1S-1 and O.11 m2 v-1S-1 respectively:
Two crystals C1 and C2, made of pure silicon, are doped with arsenic and aluminium respectively.
Why is doping of intrinsic semiconductors necessary?
Name the two types of atoms used for doping of Ge/Si.
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.
