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Structural Dynamics of Al2O3/NiAl(110) During Film Growth in NO2
Rik V Mom1, Joost Vermeer1, Joost W M Frenken1,2
1Huygens-Kamerlingh Onnes Laboratory , Niels Bohrweg 2, 2333 CA Leiden, The Netherlands.
The Journal of Physical Chemistry. B
|October 18, 2017
Summary
Investigating alumina film growth on NiAl(110) using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS), this study reveals structural dynamics and band gap states. Trenches form as the film thickens, indicating stress relief.
Area of Science:
- Materials Science
- Surface Science
- Thin Film Growth
Background:
- Continuum models describe oxide film growth, but local structural dynamics remain poorly understood.
- Investigating alumina film growth on NiAl(110) provides insight into nanoscale oxide formation mechanisms.
Purpose of the Study:
- To explore the local structural dynamics during alumina film growth on NiAl(110).
- To characterize the evolution of alumina films using advanced surface science techniques.
Main Methods:
- Utilized cyclic growth of NO2 adsorption and annealing.
- Employed scanning tunneling microscopy (STM) for high-resolution surface imaging.
- Applied X-ray photoelectron spectroscopy (XPS) for chemical state analysis.
Main Results:
- Alumina films up to 0.9 nm thick were grown via cyclic NO2 exposure and annealing.
- STM revealed vacancy island formation and subsequent AlOx filling, leading to terrace coalescence.
- XPS confirmed the insulating nature of the growing film, while STM detected states within the band gap.
- Surface trenches formed during film thickening, suggesting stress relief mechanisms.
Conclusions:
- Cyclic growth enables controlled thin alumina film formation on NiAl(110).
- The growing alumina film exhibits a finite density of states within the band gap, despite its insulating character.
- Film thickening induces surface morphology changes, indicative of stress relaxation processes.
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