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प्रश्न
With reference to semiconductor physics, answer the following question.
What is meant by “Forbidden band" of energy levels?
उत्तर
The energy difference between the valence and conduction bands is known as the forbidden band. Among its characteristics are the following: the material's current flow is caused by electrons moving from the valence band to the conduction band; there are no free electrons present.
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संबंधित प्रश्न
Draw energy band diagrams of an n-type and p-type semiconductor at temperature T > 0 K. Mark the donor and acceptor energy levels with their energies.
We have valence electrons and conduction electrons in a semiconductor. Do we also have 'valence holes' and 'conduction holes'?
The impurity atoms with which pure silicon may be doped to make it a p-type semiconductor are those of
(a) phosphorus
(b) boron
(c) antimony
(d) aluminium.
In a pure semiconductor, the number of conduction election 6 × 1019 per cubic metre. How many holes are there in a sample of size 1 cm × 1 mm?
Find the maximum wavelength of electromagnetic radiation which can create a hole-electron pair in germanium. The band gap in germanium is 0.65 eV.
(Use Planck constant h = 4.14 × 10-15 eV-s, Boltzmann constant k = 8·62 × 10-5 eV/K.)
The conductivity of an intrinsic semiconductor depends on temperature as σ = σ0e−ΔE/2kT, where σ0 is a constant. Find the temperature at which the conductivity of an intrinsic germanium semiconductor will be double of its value at T = 300 K. Assume that the gap for germanium is 0.650 eV and remains constant as the temperature is increased.
(Use Planck constant h = 4.14 × 10-15 eV-s, Boltzmann constant k = 8·62 × 10-5 eV/K.)
With reference to Semiconductor Physics,
Draw a labelled energy band diagram for a semiconductor.
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If the lattice constant of this semiconductor is decreased, then which of the following is correct?
Draw the energy band diagrams for conductors, semiconductors and insulators. Which band determines the electrical conductivity of a solid? How is the electrical conductivity of a semiconductor affected with rise in its temperature? Explain.
