Morphological evolution and growth mechanism of hierarchical structure of PbTe films grown by off-axis magnetron co-sputtering

The morphological evolution of PbTe thin films grown by off-axis co-sputtering was studied. The hierarchical structures with various shapes including pyramids, truncated octahedrons, triangular shape plates and flower shape mounds were formed on the surface by adjusting the co-sputter Telluride (Te) flux and substrate temperatures. The pyramids were favor to form under low co-sputter Te flux (<0.06 angstrom/s) at any growth temperatures between 150 degrees C and 320 degrees C. The columnar growth mode was proposed to explain the pyramid formation. The shape transitions from pyramids to truncated octahedrons and triangular shape plates were gradually taking place with the Te flux increased from 0.13 angstrom/s to 0.4 angstrom/s. The evolution was mainly attributed to the change in the ratio of growth rate between the {1 1 1} and {1 0 0} planes. The origin of flower shape mounds may be relative to the kinetic growth of these crystal habits of PbTe due to low mobility at 220 degrees C. (C) 2014 Elsevier B.V. All rights reserved.