Question

A Zener diode has a contact potential of 1V in the absence of biasing. It undergoes Zener breakdown for an electric field of \(10^6\) V/m at the depletion region of p--n junction. If the width of the depletion region is \(2.5\,\mu m\), what should be the reverse biased potential for the Zener breakdown to occur?

• A. 3.5 V
• B. 1.5 V
• C. 2.5 V
• D. 0.5 V

Hint:

Zener breakdown occurs when \(E\cdot d\) reaches a critical voltage.

Answer 1

The Correct Option is C

Step 1: Use relation between electric field and breakdown voltage.
Electric field in depletion region:
\[ E = \frac{V}{d} \Rightarrow V = E \cdot d \]
Step 2: Substitute given values.
\[ E = 10^6 \, \text{V/m},\quad d = 2.5\mu m = 2.5\times 10^{-6}\text{ m} \]
Step 3: Calculate breakdown voltage across depletion layer.
\[ V = 10^6 \times 2.5\times 10^{-6} = 2.5 \text{ V} \]
Step 4: Match with option.
Thus, reverse biased potential required is \(2.5V\).
Final Answer:
\[ \boxed{2.5V} \]