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प्रश्न
Write the two processes that take place in the formation of a p-n junction.
Name two important processes involved in the formation of a p-n junction diode.
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उत्तर
The processes of "diffusion" and "drift" are critical in a p-n junction. When the p and n-sides come into contact, the majority of carriers "diffuse" from a high concentration to a low concentration. Electrons move and combine with holes from the n-side to the p-side. Holes migrate from the p-side to the n-side in the same way that electrons and holes do at the junction. A "depletion region" is formed when the near junction area runs out of carriers and becomes charged. Current "diffusion" is caused by current "diffusion."
In the depletion area, the charge produces an electric field. The electric field creates a flow of minority carriers in the 'depletion' region. The produced current is known as "drift current," and it is referred to as drift. The directions of "diffusion and drift current" are reversed.
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संबंधित प्रश्न
In a p-n junction diode, the current I can be expressed as
I = `"I"_0 exp ("eV"/(2"k"_"BT") - 1)`
where I0 is called the reverse saturation current, V is the voltage across the diode and is positive for forward bias and negative for reverse bias, and I is the current through the diode, kBis the Boltzmann constant (8.6×10−5 eV/K) and T is the absolute temperature. If for a given diode I0 = 5 × 10−12 A and T = 300 K, then
(a) What will be the forward current at a forward voltage of 0.6 V?
(b) What will be the increase in the current if the voltage across the diode is increased to 0.7 V?
(c) What is the dynamic resistance?
(d) What will be the current if reverse bias voltage changes from 1 V to 2 V?
Explain briefly with the help of necessary diagrams, the reverse biasing of a p-n junction diode. Also draw characteristic curves.
Draw a circuit diagram to study the input and output characteristics of an n-p-n transistor in its common emitter configuration. Draw the typical input and output characteristics.
The drift current in a reverse-biased p-n junction is increased in magnitude if the temperature of the junction is increased. Explain this on the basis of creation of hole-electron pairs.
If the two ends of a p-n junction are joined by a wire,
Two identical p-n junction may be connected in series with a battery in three ways. The potential difference across the two p-n junctions are equal in
In a p.n junction, the depletion region is 400 nm wide and an electric field of 5 × 105 V m−1 exists in it. (a) Find the height of the potential barrier. (b) What should be the minimum kinetic energy of a conduction electron which can diffuse from the n-side to the p-side?
In a p-n junction, a potential barrier of 250 meV exists across the junction. A hole with a kinetic energy of 300 meV approaches the junction. Find the kinetic energy of the hole when it crosses the junction if the hole approached the junction (a) from the p-side and (b) from the n-side.
Find the equivalent resistance of the network shown in figure between the points A and B.
(Assume that the resistance of each diode is zero in forward bias and is infinity in reverse bias.)
Answer in detail.
Discuss the effect of external voltage on the width of depletion region of a p-n junction.
