Ion-beam analysis of insulator samples

Abstract

During the bombardment of insulator materials with high-energy particles, the samples are often emitting light and are sparking. This fact makes both the ion-beam analysis and the ion implantation of insulating materials more difficult. Light may disturb the detectors, sparks usually disturb the current-integration systems and electronics. Moreover, the accumulation of positive charges alters the results of the experiments via decelerating the incoming ions and accelerating the outgoing particles. In case of ion implantation, the projected range may be changed, while in ion-beam analysis the shape of the spectra can be changed resulting evaluation problems.To avoid the charge accumulation several methods have been used in the daily practice such as applying thin cover layers, wrapping or masking the samples, applying relatively low beam currents or electron sources in the experimental chamber.A short review of the above mentioned methods to avoid the charge accumulation is given. Moreover, the evaluation problems of the spectra taken on sparking (or at least charged-up) samples are also discussed. Proton and helium backscattering spectrometry as well as elastic recoil detection analysis are used to demonstrate the capability of a simple model of charge accumulation which is implemented to DEPTH code.