Assume that a p$^(+-$n$)$ diode is built with an n region width l smaller than a hole diffusion length

$\backslash$delta p$($x$\_($n$)=\backslash$infty $)=0\backslash$delta p$($x$)=$C$\_(1)$e$^(($x$)/($L$\_($p$)))+$C$\_(2)$e$^(-($x$)/($L$\_($p$)))\backslash$delta p$=0($x$\_($n$))=$l$\backslash$delta p$($x$\_($n$))\backslash$delta px$\_($n$)$p$+-$n