we want to design an implant step which will implant phosphorus ions through 50nm of sio 2 into an underlying silicon substrate such that the peak concentration in the substrate is 1 × 10 17 cm − 3 and the concentration at the sio 2 /si interface is 1 × 10 15 cm − 3 . what energy and dose would you use to achieve these conditions. assume that the stopping power of sio 2 is the same as that of silicon. neglect channeling effects.