In an abrupt $p-n$ junction, doping concentrations on $p$-side and $n$-side are $\mathrm{N}_{\mathrm{A}}=9 \times 10^{16} / \mathrm{cm}^{3}$ and $N_{0}=1 \times 10^{16} / \mathrm{cm}^{3}$ respectively. The $p-n$ junction is reverse biased and the total depletion width is $3 \; \mu \mathrm{m}$. The depletion width on the $p$-side is
- $2.7 \; \mu \mathrm{m}$
- $0.3 \; \mu \mathrm{m}$
- $2.25 \; \mu \mathrm{m}$
- $0.75 \; \mu \mathrm{m}$