$2.(2)$ A Si p$-$n junction has a cross$-$sectional area of $0\mathrm{.}001$ cm $2,$ boron doping on one side at $1016$ cm $3,$ and

phosphorous doping on the other side at $31017$ cm $3.$

For Si$,$ the electron mobility is $1350$ cm $2/($Vs$),$ the hole mobility is $480$ cm $2/($Vs$),$ the charge carrier lifetime is $2$ s$,$

the intrinsic charge carrier density is $1\mathrm{.}51010$ cm$3,$ and the dielectric constant is $11\mathrm{.}8.$

What is the contact potential?

What are the depletion region widths on the p$-$side and n$-$side and the current for a forward bias voltage of $0\mathrm{.}7$ V$.$