Fig. 7

Na-Ga affinity and defect analysis. a [²³Na]/([⁶³Cu] + [²³Na]) SIMS signal ratio plotted as a function of the corresponding [⁶⁹Ga]/([¹¹⁵In] + [⁶⁹Ga]) for three locations in the Se+Na₂Se sample with increasing Na concentrations (curved green arrow) resulting from a decreasing distance from the sodium selenide source during the PDT (numbered green arrows in schematics). Magnified views of the regions of interest in the APT maps of untreated (b) and Se+Na₂Se films (c) and d–e corresponding concentration profiles along the squared arrows. f–g STEM images of typical detects encountered in the films taken at different tilt angles