Exploring the relationship of morphology and structure to pit initiation in Cl-implanted Al thin films

Implantation of Cl into Al thin films leads to pitting in a sulfate environment, where the pitting potential decreases with increasing Cl concentration (1). Changes in film morphology, structure and composition resulting from the implantation process have been investigated here in order to more fully characterize the effects of implantation as a function of implant fluence. Sputtering of the film surface during the implantation process results in faceting at grain boundaries, as observed by atomic force microscopy, Point defect agglomerates are observed by dark field scanning transmission electron microscopy (STEM). Spectral imaging shows that the Cl concentration is locally non-uniform. Each of these effects becomes more pronounced as the implant fluence increases. The impact of these morphological, structural and compositional effects resulting from the implantation process on pitting is currently unknown.