Crystal ``Doping'' by Ion Bombardment

>The doping of metals and semiconductors with highly resolved ion beams eliminates reagent impurity contamination, provides high isotopic enrichment, and allows cross section determinations with 10/sup -8/ to 10/sup -11/ g of material thus eliminating self-shielding. To control the penetration depth of the bombarding ions in a magnetic analyzer, a variable high-voltage bias is used. In semiconductor research ionic doping is utilized to make shallow p-n or n-p junctions by impregnating a crystal of sillcon with group III or V elements. An ion bombardment technique is also being employed to determine if diffusion coefficients can be obtained by impregnating metallic filaments with a multiplicity of elements and isotopes. These lattice diffusion studies are an attempt to investigate whether the usual temperature dependence D = D/sub o/ exp (- epsilon /kT) has experimental validity on a microscopic scale. ( N.W.R.)