In a $p-n$ junction diode, the thickness of deplection layer is $2 \times 10^{-6} \mathrm{~m}$ and barrier…

In a $p-n$ junction diode, the thickness of deplection layer is $2 \times 10^{-6} \mathrm{~m}$ and barrier potential is $0.3 \mathrm{~V}$. The intensity of the electric field at the junction is
  1. $0.6 \times 10^{-6} \mathrm{Vm}^{-1}$ from $n$ to $p$ side
  2. $0.6 \times 10^{-6} \mathrm{Vm}^{-1}$ from $p$ to $n$ side
  3. $1.5 \times 10^5 \mathrm{Vm}^{-1}$ from $n$ to $p$ side
  4. $1.5 \times 10^5 \mathrm{Vm}^{-1}$ from $p$ to $n$ side

Solution

Here, the barrier voltage, $V=0.3$ volt and the width of depletion layer, $d=2 \times 10^{-6} \mathrm{~m}$ $\therefore$ Electric field at the junction, $\begin{aligned} E & =\frac{V}{d}=\frac{0.3 \mathrm{~V}}{2 \times 10^{-6} \mathrm{~m}} \\ & =1.5 \times 10^5 \mathrm{~V} / \mathrm{m} \end{aligned}$ The direction of electric field is from $n$-type to $p$-type.

Asked in: AP EAMCET 2011

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