Interface layers in Al-based reactive nanolaminates play a crucial role in the energetic properties and reactivity of such materials [1]. The onset temperature, reaction kinetics and even the stability at low temperature is greatly influenced by the composition and related microstructure of the interface. Here we present a fundamental study of the interface formation between Al and reactive oxides to arrive at detailed reaction mechanisms.CuO and ZnO are first synthesized by either Pulsed Laser Deposition or Atomic Layer Deposition and characterized by XRD and AFM. These chemically-controlled thin oxide surfaces then serve as substrate layers for e-beam evaporation of Al or gas phase modification with trimethylaluminum (TMA). The chemical modification of the surface and the location of Al atoms are studied using in-situ IR, XPS and low energy ion scattering (LEIS). First principles calculations are also used to explain the mechanism of interface formation upon Al deposition. We find that there is a propensity for Al atoms to penetrate into the oxide films. In contrast, TMA molecules adsorb on the surface, preventing Al to penetrate deep into the oxides. A quantitative investigation of the interface formation and evolution at low temperature is also performed using a nanocalorimeter, once the Al/(Cu,Zn)O nanolaminates are grown, revealing that an ultra-thin layer of Al2O3 is sufficient to stabilize (i.e. retard ignition) the Al/CuO interface. This work highlights the role of the interface and suggests methods for controlling its composition. [1] J. Kwon et al., Appl. Mater. Interfaces 2013, 5, 605-613

Fundamental study of interface layer formation in reactive Al-based reactive thin films

247th National Meeting (2014)

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