Boron is implanted into a lightly doped n$-$type Si substrate at an energy of $80$keV$.$ The dose is $210^15$cm$-2.$The Si substrate is tilted $7$with respect to the ion beam to make it appear amorphous. The implanted region is assumed to be rapidly annealed to achieve complete electrical activation $($dopant activation$).$What is the peak electron concentration produced? $($Neglect the initial lightly doped Si substrate effect.$)($Boron: E$=80$keV for Rp $=250$nm$,$Rp $=75$nm$)$