Seminar: Diffusion and Point Defects in Solids – Experiments with Neutron and X-ray Reflectometry

Diffusion and point defects (vacancies and self-interstitials) play an important role for various phenomena in application relevant and fundamental solid state research. Typical examples are grain growth, mechanical deformation, stress relaxation, ion conductivity, sensor applications, doping of semiconductors and many more. The control of diffusion and reaction of point defects on the nanometer scale is the key for the development of nanoscale devices.
In the present talk, experiments will be discussed, which are based on isotope multilayers and neutron reflectometry [1,2]. They allow the characterization of diffusion processes on the (sub)nanometer scale. Examples of recent research activities are presented for elemental semiconductors (Si, Ge), nanocrystalline Fe films, and Li ion conductors.
In the second part of the talk, synchrotron based in-situ X-ray diffraction and reflectometry studies are presented to investigate the role of vacancies for the relaxation of residual stress in thin Pt films at low temperatures [3]. The results indicate that compressive stress relaxation is due to the creation of vacancies at the free film surface.

[1] H. Schmidt et al.,  Phys. Rev. Lett. 96 (2006), 055901.
[2] H. Schmidt et al., Acta Mater. 56 (2008), 464.
[3] W. Gruber, H. Schmidt et al., Phys. Rev. Lett. 107 (2011), 265501.

Date

14.05.2012

Time

14:45–15:45

Place

Physics HS3

Garching, Garching, Deutschland

Speaker

Prof. Dr. H. Schmidt, Technische Universität Clausthal

Organizers

TUM/FRM II

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