Investigation of radiation damage in silicon by a backscattering method

The dose dependence of lattice disorder produced by implanted argon ions of energy 200 ke V has been investigated for doses between 2 × 1013/cm2 and 1 × 1017/cm2 and four implantation temperatures, -196°C, 20°C, 200°C and 400°C. The radiation damage was determined by means of the channelling technique with 1.4 MeV He+-ions. To obtain the number of displaced Si-atoms the rise of the aligned energy spectrum in an energy region corresponding to the depth behind the disordered layer was measured. In this case it is possible to describe the disordered region as an amorphous surface layer leading to multiple scattering of the beam. The accuracy of a well-known thickness and maximal deviations of no more than 10% were obtained. The results for the total number N T of disordered Si-atoms show for lower doses a more than proportional increase with the dose N I and for higher doses the well-known saturation effects connected with the complete amorphization of the surface layer.