GATE 2018 EC – Question 28
A p-n step junction diode with a contact potential of 0.65 V has a depletion width of 1 $\mu$m at equilibrium. The forward voltage (in volts, correct to two decimal places) at which this width reduces to 0.6 $\mu$m is ________.
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Correct answer: 0.41 to 0.43
Explanation
The depletion width varies as $W\propto\sqrt{V_{bi}-V}$, so $\frac{0.6}{1}=\sqrt{\frac{0.65-V}{0.65}}$. Then $0.65-V=0.36\times0.65=0.234$ and $V=0.416\approx0.42$ V.