Ion implantation is now a well-established technique for fabricating semiconductor devices and recently has received increasing application in the fields of metallurgy1and materials science2as a unique means of changing to advantage the composition, and mechanical and chemical properties of a substrate surface. Before one can begin to explain the observed changes in the surface properties of the implanted materials it is essential that the ion range and collection characteristics be known. Fundamentally, ion-range measurements are useful for comparison with theoretical ranges to check the validity of the long- accepted method of treating the energy loss of energetic ions in solids developed by Lindhard, Scharff and Schiø3(hereafter termed US).