In a $p-n$ junction diode, the thickness of the depletion layer is $2 \times 10^{-6} \,m$ and the barrier potential is $0.3 \,V$. The intensity of the electric field at the junction is

• A
  $0.6 \times 10^{-6} \,Vm^{-1}$ from $n$ to $p$ side
• B
  $0.6 \times 10^{-6} \,Vm^{-1}$ from $p$ to $n$ side
• C
  $1.5 \times 10^5 \,Vm^{-1}$ from $n$ to $p$ side
• D
  $1.5 \times 10^5 \,Vm^{-1}$ from $p$ to $n$ side