Q3. Draw energy level diagram for an
a) unbiased p-n junction diode
b) forward biased p-n junction diode and explain how the barrier potential changes.
(a) Energy level diagram for unbiased p-n junction diode is as follows-
(b) Energy level diagram for forward biased p-n junction diode is as follows-
When the junction is unbiased, negative charge resides in p-side and positive charge resides in n-side. But when forward biased is applied, positive charge from p-side enters into n-side and negative charge from n-side enters into p-side. Thus, charge densities of both types reduce and hence, potential barrier reduces.
in forward bias potential barrier decreases & increases in reverse bias
in f.b. p- iS connected to positive of the battery & 'n' to negative of battery
in R.B. it is vice-versa
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