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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.
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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 ______.
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Explain the following term:
Intrinsic semiconductor
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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.
What is an intrinsic semiconductor?
Which relation gives the electron concentration, hole concentration, and intrinsic carrier concentration in an intrinsic semiconductor?
How does the conductivity of an intrinsic semiconductor change when temperature rises?
What first enables a valence electron to move to the conduction band?
Which charge carriers contribute to conduction in an intrinsic semiconductor?
How does the conductivity of an intrinsic semiconductor compare with that of an extrinsic semiconductor?
Which pairing correctly identifies examples of intrinsic and extrinsic semiconductors?
What does a classroom in which every student is seated represent in the description of a semiconductor at very low temperature?
Why are pure semiconductors not usually used directly in most electronic devices?
