Advertisements
Advertisements
Questions
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.
Advertisements
Solution
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.
APPEARS IN
RELATED QUESTIONS
Explain briefly with the help of necessary diagrams, the forward biasing of a p-n junction diode. Also draw characteristic curves.
The diffusion current in a p-n junction is
Diffusion current in a p-n junction is greater than the drift current in magnitude
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.)
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.

An AC source is connected to a diode and a resistor in series. Is the current thorough the resistor AC or DC?
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 __________ .
p-n junction diode is formed
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 ______.
