Effect of lattice voids on Rutherford backscattering dechanneling in tungsten

Abstract

The response of Rutherford backscattering spectrometry in channeling mode through a dechanneling mechanism to the presence of voids in crystals has been considered to be qualitatively weak. However there is a lack of the validation of its quantitative behavior. In this work, we present an investigation on the dechanneling induced by voids with different shapes in tungsten based on a simulation approach. We observe that dechanneling cross section of large voids is indeed found as a product of the minimum yield and the area projected from the void to the target surface as suggested by analytical models in literature. However, this method overestimates the dechanneling induced by small voids, in which the spatial distribution of incident ions inside a target has a non-negligible effect. We found that an inter-void distance effect is able to further lower dechanneling signals if the inter-void distance is small. When small spherical voids coalesce into a group of larger ones, the dechanneling fraction is not expected to increase. In addition, comparisons between voids and stacking faults show that there are significant discrepancies between these two defects in terms of dechanneling.