June 2013

Using vapour deposition methods small deviations of process parameters (substrate temperature, process pressure, etc.) can alter the resulting morphology of the sample significantly. Furthermore, targets used for pulsed laser deposition are exposed to high energy densities and thus can undergo structural changes. The images shown above shall illustrate these aspects. PbTe crystallizes in a rock salt structure. Therefore, trigonal patterns are characteristic of (111)- and quadratic patterns of (200)-crystallite orientation. By modifying the process pressure, different preferred orientations could be realized (independently from the substrate). The scanning electron micrographs (a) and (b) reveal preference of (111)-orientation and (c) of (200)-orientation respectively. Variations of target constitution due to impinging laser beams are exemplarily shown in (d) by a resulting columnar structure of Na0.7CoO2. (Picture submitted by Patrick Schichtel and Christian Schneider)