Glancing angle XAFS and X-ray reflectivity studies of transition-metal/aluminium interfaces

The combination of glancing angle X-ray absorption fine structure (XAFS) and X-ray reflectivity measurements provide detailed structural information about interfaces. Results from transition-metal/Al interfaces are used to illustrate the capabilities of the techniques. Reflectivity measurements are used to determine the thickness and density profile of the films, along with the amount of interfacial or surface roughness. The XAFS measurements provide information about the local bonding at the interface, and are well suited for studying the interfacial chemistry. Of interest is the role of impurities such as oxygen in modifying interface structure and thermal stability. For Cu/Al, Ni/Al and Cr/Al a small amount of interfacial oxygen is found to affect strongly both the initial interface structure, and the response of the interface to thermal annealing. For Ni/Al it is also found that interfacial oxygen affects primarily the interface reaction, while oxygen within the Al layer suppresses the grain boundary reaction channel.