Heavy ion ERD of nitrides with a position-sensitive gas ionization detector

A gas ionization detector with novel design features has been developed for the compositional depth-profiling of materials with Elastic Recoil Detection (ERD) using very heavy incident beams. The detector features a large solid angle and thus has high detection efficiency. The detection of the ion position using a saw-tooth AE electrode within the anode is energy and species independent and enables the correction of kinematic energy broadening. The energy information is obtained from a single grid-electrode, which considerably simplifies data analysis. All chemical elements, including hydrogen, can be detected simultaneously with similar sensitivity. While it is versatile and applicable to many materials, the technique has unique capabilities when applied to thin films containing carbon, nitrogen or oxygen in combination with heavier elements and hydrogen. In contrast to other techniques, heavy ion ERD resolves all elements in a single measurement and the experimental uncertainty is limited only by counting statistics. However, the desorption of some elements, such as nitrogen or hydrogen, during the analysis can be significant. For the GaN films studied, the nitrogen and hydrogen desorption rates were found to be linear with dose. This allowed accurate extrapolations to zero dose retaining the precision of the measurement. In contrast, no nitrogen desorption occurred for nitrided steel samples enabling nitrogen depth-profiles to be extracted.