Explain the forward and reverse characteristics of the $p-n$ junction diode by drawing the circuit and graph.

(N/A) $1$. Forward Bias: When the $p$-region is connected to the positive terminal and the $n$-region to the negative terminal of an external voltage source,the diode is in forward bias. The depletion region narrows,and current increases exponentially with voltage after the threshold voltage (approx. $0.7 \ V$ for Silicon).
$2$. Reverse Bias: When the $p$-region is connected to the negative terminal and the $n$-region to the positive terminal,the diode is in reverse bias. The depletion region widens,and only a very small reverse saturation current (in $\mu A$) flows due to minority carriers. At a specific voltage called breakdown voltage $(V_{br})$,the current increases sharply.