The collection of ions implanted in semiconductors. II. range distributions derived from collection and sputter-etch curves

Abstract

Collection curves for the implantation of the heavy ions Kr and Tl into the semiconductors GaAs, Gap, Ge and Si are analysed using a previously published theory. Sputter-etch experiments in which previously implanted ions are released by further sputtering are also described. The data from both collection and sputter-etch experiments provide information on the implanted ion concentration profile and on the differential ion range probability distribution. Results indicate that the latter distribution is wider than the expected Gaussian and that values of the sputtering coefficient necessary to match the experimental range profiles to the theoretical profiles are far larger than would be expected for target erosion. These results show that other processes than simple target sputtering are important both in determining the saturation of a target in collection experiments and in the erosion of the target to reveal the implant profile in sputter-etch experiments. The very high implant concentrations reached in these studies will have metallurgical effects on the target with a resulting change in the sputtering process.