In a semiconductor $p-n$ diode,the doping concentrations on $p$-side and $n$-side are $10^{15} \text{ atoms/cm}^3$ and $10^{18} \text{ atoms/cm}^3$,respectively. Which one of the following statements is true?

• A
  Widths of depletion region on either side of the interface are equal
• B
  The depletion region width is more on $p$-side compared to that in $n$-side
• C
  The depletion region width is more on $n$-side compared to that in $p$-side
• D
  No depletion region forms because of unequal doping concentrations on $p$ and $n$-sides