only p-region is heavily doped

only $n$-region is heavily doped

Both $p$ and $n$ regions are heavily doped

Both $p$ and $n$ regions are lightly doped

$10 \mathrm{~mA}, 5 \mathrm{~mA}, 5 \mathrm{~mA}$

$15 \mathrm{~mA}, 7.5 \mathrm{~mA}, 7.5 \mathrm{~mA}$

$12.5 \mathrm{~mA}, 5 \mathrm{~mA}, 7.5 \mathrm{~mA}$

$12.5 \mathrm{~mA}, 7.5 \mathrm{~mA}, 5 \mathrm{~mA}$

top of the valence band

bottom of the conduction band

bottom of the valence band

top of the conduction band