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प्रश्न
Answer in detail.
Discuss the effect of external voltage on the width of depletion region of a p-n junction.
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उत्तर
- A p-n junction can be connected to an external voltage supply in two possible ways.
- A p-n junction is said to be connected in a forward bias when the p-region connected to the positive terminal and the n-region is connected to the negative terminal of an external voltage source.
- In forward bias connection, the external voltage effectively opposes the built-in potential of the junction. The width of the depletion region is thus reduced.
- The second possibility of connecting the p-n junction is in a reverse-biased electric circuit.
- In reverse bias connection, the p-region is connected to the negative terminal and the n-region is connected to the positive terminal of the external voltage source. This external voltage effectively adds to the built-in potential of the junction. The width of the potential barrier is thus increased.
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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 forward biasing of a p-n junction diode. Also draw characteristic curves.
A student wants to use two p-n junction diodes to convert alternating current into direct current. Draw the labelled circuit diagram she would use and explain how it works.
Explain, with the help of a circuit diagram, the working of a photo-diode. Write briefly how it is used to detect the optical signals.
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.
Explain, with the help of a circuit diagram, the working of n-p-n transistor as a common emitter amplifier.
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.
The diffusion current in a p-n junction is
Diffusion current in a p-n junction is greater than the drift current in magnitude
A hole diffuses from the p-side to the n-side in a p-n junction. This means that
In a p-n junction with open ends,
(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) new holes and conduction electrons are produced continuously throughout the material
(b) new holes and conduction electrons are produced continuously throughout the material except in the depletion region
(c) holes and conduction electrons recombine continuously throughout the material
(d) holes and conduction electrons recombine continuously throughout the material except in the depletion region.
The potential barrier existing across an unbiased p-n junction is 0.2 volt. What minimum kinetic energy a hole should have to diffuse from the p-side to the n-side if (a) the junction is unbiased, (b) the junction is forward-biased at 0.1 volt and (c) the junction is reverse-biased at 0.1 volt?
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 drift current in a p-n junction is 20.0 µA. Estimate the number of electrons crossing a cross section per second in the depletion region.
Each of the resistance shown in figure has a value of 20 Ω. Find the equivalent resistance between A and B. Does it depend on whether the point A or B is at higher potential?
Find the currents through the resistance in the circuits shown in figure.
(Assume that the resistance of each diode is zero in forward bias and is infinity in reverse bias.)
What are the readings of the ammeters A1 and A2 shown in figure. Neglect the resistance of the meters.
(Assume that the resistance of each diode is zero in forward bias and is infinity in reverse bias.)
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.)
Choose the correct option.
Current through a reverse-biased p-n junction increases abruptly at:
If in a p-n junction diode, a square input signal of 10 V is applied as shown Then the output signal across RL will be ______
In a semiconductor diode, the barrier potential offers opposition to only ______.
Zener breakdown occurs in a p-n junction having p and n both:
For an ideal diode, in forward and reverse biased condition the resistance is respectively ______.
Diode and resistance are connected as shown in figure. Out of the following statements which one is TRUE?
