Question

A Zener diode has a contact potential of $1.5\text{V}$ in the absence of biasing. It undergoes Zener breakdown for an electric field of ${10}^6\text{V/m}$ at the depletion region of $p-n$ junction. If the width of the depletion region is $2.5\mu \text{m}$, ______ be the reverse biased potential $\left(\text{in V}\right)$ for the Zener breakdown to occur.

• A. $1$
• B. $2$
• C. $4$
• D. $3$

Answer 1

The correct option is A $1$

Given:

$E={10}^6\text{V/m}$

width of the depletion region,

$d=2.5\mu \text{m}=2.5\times {10}^{-6}\text{m}$

Now, breakdown potential, $V=Ed={10}^6\times 2.5\times {10}^{-6}=2.5\text{V}$

So, the reverse biased potential for breakdown,

$V_Z=V-V_{\text{contact potential}}=2.5-1.5=1\text{V}$

Hence, option $\left(A\right)$ is the correct answer.