Dresden 2014 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 35: Poster I: Application of thin films; Focus session: Sensoric micro and nano-systems; Focus Session: Sustainable photovoltaics with earth abundant materials; Graphen (joint session with TT; MA; HL; DY; O); Ion and electron beam induced processes; Layer properties: electrical, optical, and mechanical properties; Magnetic/organic interfaces, spins in organics and molecular magnetism; Micro- and nanopatterning (jointly with O); Organic electronics and photovoltaics (jointly with CPP, HL, O); Thermoelectric materials

DS 35.46: Poster

Mittwoch, 2. April 2014, 17:00–20:00, P1

Thin film stress evolution during deposition and interrupts: a thermodynamical assessment — •Amirmehdi Saedi and Marcel J. Rost — kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands

During Volmer-Weber thin film growth at conditions with sufficiently high atom mobility, the intrinsic film stress becomes compressive in the later stages. Moreover, upon deposition interruptions, the film reacts with a huge tensile jump, that surprisingly, is fully restored back to the original stress values before the interruption, if the deposition is switched on again.

Several mechanisms have been proposed to explain these phenomena, but none of them were able to explain all the details of the experimental results and they remain as mere hypotheses waiting for their proof to come. One suggestion is that the diffusion of adatoms into/out of the grain boundaries during the deposition/interruption would be responsible for the observed effects. There are some models, based on kinetic arguments, attempting to show that this mechanism is capable of reproducing the experimental observations. However all of these models suffer from a critical shortcoming as they do not take into account the thermodynamical aspects. These include e.g. relationships between the flux, adatom densities, chemical potentials of the surface and grain boundaries, and the elastic energy of the bulk. Here our aim is to check for the first time whether the adatom-GB theory can really survive the test of a rigorous thermodynamical analysis.