Question

Consider an abrupt PN junction (at $T=300K$ ) shown in the figure.The depletion region width $x_n$ on the N-side of the junction is $0.2\mu m$ and the permittivity of silicon $\left({ϵ}_{Si}\right)$ is $1.044\times {10}^{-12}F/cm$. At the junction, the approximate value of the peak electric field (in kV/cm) is

Answer 1

For abrupt $P^{+}N$ junction
$E_{max}$ is given :
$E_{max}=\frac{-q{N}_D{x}_n}{{ϵ}_s}$ $\left[\begin{array}{c}\because N_A>>N_D\\ W\simeq x_n\end{array}\right]$ $\Rightarrow E_{max}=\frac{-1.6\times {10}^{-19}\times {10}^{16}\times 0.2\times {10}^{-4}}{1.044\times {10}^{-12}}$
$E_{max}=-30.65\times {10}^{3}V/cm$
$E_{max}=-30.65kV/cm$