Dresden 2009 – wissenschaftliches Programm
DS 9.5: Vortrag
Dienstag, 24. März 2009, 10:30–10:45, GER 37
Surface and Surface Self-diffusion of Pt thin films on Si3N4/Si and ZrO2 Substrates — •Henning Galinski, Thomas Ryll, Pierre Elser, Anja Bieberle-Hütter, Jennifer Rupp, and Ludwig Gauckler — Nonmetallic Inorganic Materials, ETH Zurich, Zurich, Switzerland
Metals and ionic bonded ceramics possess distinct diametric bonding characteristics. Thus, the stability of a metal thin film on a ceramic substrate is conditioned by the interactions between the different bonding types across the interface. In the case of weak adhesion the minimization of free surface energies gives rise to decomposition and agglomeration of thin metallic films. The morphological evolution of Pt thin films has been investigated by means of scanning electron microscopy (SEM) and atomic force microscopy (AFM). Pt thin films were deposited on Si3N4/Si and yttria stabilized ZrO2 substrates and subjected to heat treatments up to 800∘C for 2 hours. Three main observations have been made: i) the dominating mechanism of initial film rupture is the nucleation of holes at the triple junctions of the Pt thin film as shown by means of Minkowski measures. ii) The evolution of the film at this stage is in agreement with Brandon and Bradshaw’s theory of surface energy driven diffusion. The kinetics of the hole growth were used to calculate the surface self-diffusion coefficient of Pt. iii) at high temperature, holes coalesce and Pt islands are formed that undergo an Ostwald ripening process. The evolution of the particle size distribution allowed deducing the mass transfer surface diffusion coefficient of Pt on Si3N4 and ZrO2.