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प्रश्न
Distinguish between a conductor and a semi conductor on the basis of energy band diagram
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उत्तर
Distinction between conductor and insulator:
Conductor: In a conductor, the valance band is either partially filled or completely filled.
It has zero forbidden energy gap between the conduction band and the valance band.
The energy band diagram can be represented as shown below:
Insulator: In an insulator, the valance band is completely filled and the conduction band is empty.
The forbidden energy gap between the conduction band and the valance band is greater than or equal to 3 eV
The energy band diagram can be represented as shown below:
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संबंधित प्रश्न
Draw the necessary energy band diagrams to distinguish between conductors, semiconductors and insulators.
How does the change in temperature affect the behaviour of these materials ? Explain briefly.
How many 1s energy states are present in one mole of sodium vapour? Are they all filled in normal conditions? How many 3s energy states are present in one mole of sodium vapour? Are they all filled in normal conditions?
In a semiconductor,
(a) there are no free electrons at 0 K
(b) there are no free electrons at any temperature
(c) the number of free electrons increases with temperature
(d) the number of free electrons is less than that in a conductor.
The band gap for silicon is 1.1 eV. (a) Find the ratio of the band gap to kT for silicon at room temperature 300 K. (b) At what temperature does this ratio become one tents of the value at 300 K? (Silicon will not retain its structure at these high temperatures.)
(Use Planck constant h = 4.14 × 10-15 eV-s, Boltzmann constant k = 8·62 × 10-5 eV/K.)
The conductivity of a pure semiconductor is roughly proportional to T3/2 e−ΔE/2kT where ΔE is the band gap. The band gap for germanium is 0.74 eV at 4 K and 0.67 eV at 300 K. By what factor does the conductivity of pure germanium increase as the temperature is raised from 4 K to 300 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.)
The energy of a hydrogen atom in the ground state is −13.6 eV. The energy of a He+ ion in the first excited state will be:
The valance of an impurity added to germanium crystal in order to convert it into p-type semiconductor is
Which one of the following elements will require the highest energy to take out an electron from them?
Pb, Ge, C and Si
With reference to semiconductor physics, answer the following question.
In which material “Forbidden band” is absent?
