Papers by Keyword: Faceting

Abstract: In this study, we compare the electrical properties of MOS capacitors fabricated on different surface morphologies. Comparing a standard, low-roughness (<1nm), surface with one with a roughness of ~40nm, characterized by big macrosteps and large terraces. We compared the two surfaces for different thermal oxide thicknesses, ranging from d_Ox = 3.6 nm to d_Ox = 32 nm. The extracted interface state traps (D_it) shows a small, but systematic, decrease of ~10-15 % for the samples with macrosteps.

Abstract: The aim of this study was to find conditions allowing the "natural" formation of a regular and controllable step bunched morphology on a 4H-SiC seed without the need of any SiC deposition. This was performed by melting a bulk piece of Si on a 4°off 4H seed in the temperature range of 1500 - 1600°C, for 15 min. After etching the remaining Si, the 4H surface was found to be successfully highly step bunched with steps very parallel and regular. A mechanism of dissolution-precipitation was proposed, which could occur both on a short (step to step) and long (centre to periphery) range. This process is kinetically limited at low temperature (1500-1550°C) and considered to be close to the equilibrium at 1600°C.

Abstract: The faceting and migration behavior of low angle <100> grain boundaries in high purity aluminum bicrystals was investigated. In-situ technique based on orientation contrast imaging was applied. In contrast to the pure tilt boundaries, which remained straight/flat and immobile during annealing at elevated temperatures, mixed tilt-twist boundaries readily assumed a curved shape and steadily moved under the capillary force. Computational analysis revealed that this behavior is due to the inclinational anisotropy of grain boundary energy, which in turn depends on boundary geometry – the energy of pure tilt low angle <100> boundaries is anisotropic, whereas that of mixed tilt-twist boundaries isotropic with respect to boundary inclination.

Abstract: In this paper, we characterized atomic structure of a Σ = 3, [110]/{112} grain boundary in a yttria-stabilized cubic zirconia bicrystal. High-resolution transmission electron microscopy (HRTEM) clearly revealed that the grain boundary migrated to form {111}/{115} periodical facets, although the bicrystal was initially joined so as to have the symmetric straight boundary plane of {112}. Atomic-scale process for the facet growth could be modeled by the continuous flippings of atoms at the boundary core.

Abstract: The kinetic and structural behavior of symmetrical <100> tilt grain boundaries with rotation angles 8.4°, 12.0°, 14.3° and 16.0° were investigated in-situ in a hot stage SEM in the temperature range between 380°C and 640°C. The results revealed that depending on the rotation angle the boundary either remained straight, became faceted or curved under the driving force provided by the boundary surface tension during high temperature annealing. The transition “facetedcurved boundary” was also found to depend on temperature. The observed behavior is attributed to the anisotropy of grain boundary energy with respect to boundary inclination.

Abstract: Diffusional growth of the grain boundary (GB) groove permits one to measure the ratio between GB energy sGB and surface energy ssur. The faceting of twin tilt grain boundaries in Cu has been studied using the GB thermal groove method. No rough facet edges were observed. It means that melting temperature is lower than the roughening temperature for the observed facets in Cu. The influence of orientation and misorientation deviation Dq = ½q – qS½ from coincidence misorientation qS has been studied. By increase of Dq the energy of (100)CSL facet increases. The convenient method for construction 3D three-dimensional Wulff diagrams was found. The 3- dimensional Wulff diagrams were constructed using this method and measured sGB / ssur values.