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प्रश्न
Explain briefly with the help of necessary diagrams, the forward biasing of a p-n junction diode. Also draw characteristic curves.
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उत्तर
p-n junction diode under forward bias
p-side is connected to positive terminal and n-side to the negative terminal.
Applied voltage drops across the depletion region.
Direction of applied voltage (V) is opposite to the build in potential (V0).
As the depletion layer width decreases, the barrier height is reduced.
Effective barrier height under forward bias is (V0 − V).
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Electron in n-region moves towards the p-n junction and holes in p-region move towards the junction. The width of the depletion layer decreases and hence, it offers less resistance.
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Diffusion of majority carriers takes place across the junction.
This leads to forward current.
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संबंधित प्रश्न
In an unbiased p-n junction, holes diffuse from the p-region to n-region because ______.
The drift current in a p-n junction is
The diffusion current in a p-n junction is
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(a) there is no systematic motion of charge carries
(b) holes and conduction electrons systematically go from the p-side to n-side and from the n-side to p-side respectively
(c) there is no net charge transfer between the two sides
(d) there is a constant electric field near the junction.
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.
The current−voltage characteristic of an ideal p-n junction diode is given by \[i = i_0 ( e^{eV/KT} - 1)\] where, the drift current i0 equals 10 µA. Take the temperature T to be 300 K. (a) Find the voltage V0 for which \[e^{eV/kT} = 100 .\]One can neglect the term 1 for voltages greater than this value. (b) Find an expression for the dynamic resistance of the diode as a function of V for V > V0. (c) Find the voltage for which the dynamic resistance is 0.2 Ω.
(Use Planck constant h = 4.14 × 10-15 eV-s, Boltzmann constant k = 8·62 × 10-5 eV/K.)
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Calculate the current through the circuit and the potential difference across the diode shown in figure. The drift current for the diode is 20 µA.
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.)
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