SATHEE: semiconductor-electronics--materials-devices-and-simple-circuits Question 39

सेमीकंडक्टर इलेक्ट्रॉनिक्स सामग्री उपकरण और सरल सर्किट

Question: Q. 5. Explain with the help of suitable diagram, the two processes which occur during the formations of a $p - n$ junction diode. Hence define the terms (i) depletion region and (ii) potential barrier.

(b) Draw a circuit diagram of a $p - n$ junction diode under forward bias and explain its working.

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Solution:

Ans. (a) Explaining the two processes } & 1+1 \ \text { Defining the two terms } & 1 / 2+1 / 2\end{array}$

(b) Circuit diagram

Working

(a) The two important processes are diffusion and drift. Due to concentration gradient, the electrons diffuse from the $n$ side to the $p$ side and holes diffuse the $p$ side to the $n$ side.

$1 / 2$ Electron drift $\overset{⟷}{\to}$ Electron diffusion

Due to the diffusion, an electric field develops across the junction. Due to the field, an electron moves from the $p$ -side. The flow of the charge carriers due to the electric field, is called drift. $1 / 2$

(i) Depletion region :

It is the space charge region on either side of the junction, that gets depleted of free charges. is known as the depletion region.

(ii) Potential Barrier :

The potential difference, that gets developed across the junction and opposes the diffusion of charge carries and brings about a condition of equilibrium, is known as the barrier potential. 1/2

(b) Try yourself similar to Q. 5 SAT Question-II

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