Advertisements
Advertisements
Question
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.
Advertisements
Solution
Given:
Potential barrier, d = 250 meV
Initially,
Kinetic energy of a hole = 330 meV
We know that the kinetic energy of a hole decreases when the junction is forward biassed (because of the energy loss in crossing the junction).
Also, the kinetic energy of a hole increases when the junction is reverse biassed (because reverse bias voltage pushes the hole on the n-side towards the junction) in the given the p-n junction diode.
(a) The kinetic energy of a hole decreases under forward bias.
∴ Final kinetic energy = (300 − 250) meV
= 50 meV
(b) The kinetic energy of a hole increases under reverse bias.
∴ Final kinetic energy = (300 + 250) meV
= 550 meV
APPEARS IN
RELATED QUESTIONS
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?
Write the two processes that take place in the formation of a p-n junction.
A zener diode is fabricated by heavily doping both p- and n- sides of the junction. Explain, why?
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.
Mention the important considerations required while fabricating a p-n junction diode to be used as a Light Emitting Diode (LED). What should be the order of band gap of an LED if it is required to emit light in the visible range?
Explain, with the help of a circuit diagram, the working of n-p-n transistor as a common emitter amplifier.
How is a zener diode fabricated so as to make it a special purpose diode? Draw I-V characteristics of zener diode and explain the significance of breakdown voltage.
Explain briefly, with the help of a circuit diagram, how a p-n junction diode works as a half wave rectifier.
The drift current in a p-n junction is
Diffusion current in a p-n junction is greater than the drift current in magnitude
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 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.
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 current through the battery in each of the circuits shown in figure.
(Assume that the resistance of each diode is zero in forward bias and is infinity in reverse bias.)
Find the current through the resistance R in figure if (a) R = 12Ω (b) R = 48Ω.
(Assume that the resistance of each diode is zero in forward bias and is infinity in reverse bias.)
A load resistor of 2kΩ is connected in the collector branch of an amplifier circuit using a transistor in common-emitter mode. The current gain β = 50. The input resistance of the transistor is 0.50 kΩ. If the input current is changed by 50µA. (a) by what amount does the output voltage change, (b) by what amount does the input voltage change and (c) what is the power gain?
A diode, a resistor and a 50 Hz AC source are connected in series. The number of current pulses per second through the resistor is __________ .
Choose the correct option.
Current through a reverse-biased p-n junction increases abruptly at:
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?
