1. In a method of obtaining the distribution profile of electrically active ions implanted into a semiconductor, the improvement comprising: providing an integral target of said semiconductor having a plurality of doped regions of different known background impurity concentrations of one type conductivity, respectively, formed therein, each of said doped regions having a substantially uniform background impurity concentration and having a surface comprising a portion of the surface of said integral target, and ion implanting ions of an opposite type conductivity through the surface of said integral target and simultaneously into each of said doped regions to form a P-N junction in each of said doped regions.