The channeling characteristics of protons and helium ions in variousdiamond-type lattices (diamond, Si, Ge, GaP, GaAs, GaSb) have beenstudied by means of elastic backscattering in the 0.5 to 2 MeV range.Critical angles (ψ½) and minimum yields (ψ½) have been measured andcompared to theory. The values of ψ½ for axial channeling have a functionaldependence which agrees well with calculations based on the averagepotential along the row - both for uniform and for non-uniform spacingand (in the case of the compound semiconductors) for mixed atomiccomposition. Planar critical angles also show a functional dependencein agreement with average potential calculations. However, it is necessaryto include in the calculation the effect of surface transmissionwhich becomes increasingly important for higher order planar directions(e.g. lower atomic density of the planes). Measured full angular distributionsare compared with calculated distributions for planar channeling. For both axial and planar channeling the measured criticalangles are ≈ 25% lower in absolute magnitude than calculated.
Channeling and electrical measurements are combined to study ionimplanted impurities in silicon. The lattice disorder and impurity atomlattice location are investigated by channeling effect measurementsusing a 1 MeV helium ion analyzing beam. The electrical type, number ofcarriers/cm2 and mobility are determined by use of Hall effect and sheetresistivity measurements.
The anneal behavior of Cd and Te implantations (20-50 keV) into Siat substrate temperatures of 23°C and 350°C were investigated. The roomtemperature Te implants showed substitutional behavior and donor actionafter anneal at 600°C. In room temperature Cd implantations, outdiffusionof the Cd was observed when the disordered layer annealed. Implantationsof Cd at 350°C indicated the presence of an interstitialcomponent and n-type behavior was observed.
