In a p$+-$n Si junction, the n$-$side has a donor concentration of $1016$ cm$-3.$ If ni$=1010$ cm$-3,$ relative

dielectric constant $$r$=12,$ calculate the depletion width at a reverse bias of $100$ V$.$ What is the

electric field at the mid$-$point of the depletion region on the n side? $($Hints: $($a$)$ p$+$ means very

heavily doped. $($b$)$ under reverse bias the potential barrier height changes from V$0$ to V$0-$VR$,$ where

VR $=-100$ V$.($c$)$ dielectric constant $=0$r$,$ where $0$ is vacuum dielectric constant, $8\mathrm{.}8510-12$ F$/$m$.)$