Measurements of ranges and variances of 1–20 keV N and O ions implanted in Be and C 0.83H 0.17 by means of RBS with a 4He beam at 350 keV

Abstract

A simple and convenient technique for depth profiling implanted ions at high resolution is to use a H or He beam at low energy (<1 MeV) where the stopping power is maximum. N was implanted with energies ranging from 3 to 20 keV into Be and O was implanted with energies ranging from 1 to 13 keV into C 0.83H 0.17 film. A He beam delivered by a low energy (350 keV) Van de Graaff accelerator was used to depth profile the implanted ions by means of Rutherford backscattering spectrometry (RBS). At this energy, the depth resolution is 10 nm at the surface and 13.7 nm at 100 nm depth in Be, and 6.2 nm at the surface and 9.2 nm at 100 nm depth in C. Thus reliable depth distribution of implanted ions can be obtained. Mean ranges and variances have been extracted from the depth distributions and plotted as a function of the implanted energy. The sputtering of the surface sample induced by these low energy implantations was taken into account for the evaluation of the ranges and variances. The results were compared to the predictions of Monte Carlo codes TRIM-95 and TRIM.SP. A good agreement between experimental results and TRIM.SP predictions was obtained with the use of the interaction potential of krypton-carbon, the stopping cross section of Lindhard-Scharff with a correction factor c k ≈ 1.0 and the Firsov screening with no correction factor.