A transmission electron microscopy study of xenon bubbles in ion-implanted tin

This paper describes a transmission electron microscopy (TEM) study of a body-centred-tetragonal metal (β tin) after room temperature implantation with 40 keV xenon ions. At low to medium doses, dark-field microscopy showed that a large fraction of the bubbles present (those with diameters less than 5 nm) contained solid xenon precipitates. From the inferred bubble pressures, it was demonstrated that these bubbles were in equilibrium, as expected from the high homologous implant temperature. At the highest dose, a large range of bubble sizes was found with strongly facetted bubbles having edge lengths in excess of 100 nm. Further results were obtained using a microscope cooling holder to follow the freezing of xenon in medium and large sized bubbles. The details of the gas adsorption on the bubble facets was deduced and the xenon content of the larger bubbles estimated. Of particular interest was that the xenon content of the larger bubbles suggested that they were grossly underpressurized, in contrast with the coexisting small equilibrium bubbles. The bimodal nature of the bubbles is discussed using the critical radius concept within the framework of bias-driven cavity growth.