A Si sample is uniformly doped with phosphorus at 5 E 16 cm^-3. We make a p-n junction by implanting boron atoms into the surface layer. The implanted depth is 0.15 µm. What should the surface concentration of the boron implant be in order to obtain a p-n junction with equal concentrations of holes in the p-region and electrons in the n-region? Assume the 100% implant activation.