Seeding Process (seeding + process)

Distribution by Scientific Domains


Selected Abstracts


Numerical investigation of heat transport and fluid flow during the seeding process of oxide Czochralski crystal growth Part 1: non-rotating seed

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2007
M. H. Tavakoli
Abstract For the seeding process of oxide Czochralski crystal growth, the flow and temperature field of the system as well as the seed-melt interface shape have been studied numerically using the finite element method. The configuration usually used initially in a real Czochralski crystal growth process consists of a crucible, active afterheater, induction coil with two parts, insulation, melt, gas and non-rotating seed crystal. At first the volumetric distribution of heat inside the metal crucible and afterheater inducted by the RF coil was calculated. Using this heat source the fluid flow and temperature field were determined in the whole system. We have considered two cases with respect to the seed position: (1) before and (2) after seed touch with the melt. It was observed that in the case of no seed rotation (,seed = 0), the flow pattern in the bulk melt consists of a single circulation of a slow moving fluid. In the gas domain, there are different types of flow motion related to different positions of the seed crystal. In the case of touched seed, the seed-melt interface has a deep conic shape towards the melt. It was shown that an active afterheater and its location with respect to the crucible, influences markedly the temperature and flow field of the gas phase in the system and partly in the melt. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Diamond Seeding and Growth of Hierarchically Structured Films for Tissue Engineering,

ADVANCED ENGINEERING MATERIALS, Issue 7 2009
Alexander Kromka
The importance of using optimized diamond powder suspension for an efficient seeding process is shown to be crucial for the growth of hierarchically structured nanocrystalline diamond (NCD) films. The morphology of freshly adhered human osteoblastic cells (SAOS-2) on such structured NCD films is significantly influenced by the substrate roughness. The hierarchically structured NCD films can thus find application in cell cultivation implants and tissue engineering. [source]


Role of polymers in CVD growth of nanocrystalline diamond films on foreign substrates

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11-12 2009
A. Kromka
Abstract Spin coating of PVA polymer with fine grained diamond powder is used as the nucleation treatment for achieving growth of nanocrystalline diamond (NCD) thin films. The growth is realized by standard microwave plasma chemical vapor deposition (CVD). The morphology and character of deposited NCD film is strongly related to the growth temperature. The low temperature process (430°C) results in a growth of well-faceted continuous films. The high temperature process (830,°C) results in voids and openings in the layer. Addition of PVA as the interlayer between the substrate and the seeding polymer composite leads to more openings. The effect is the most pronounced at 830,°C. This is assigned to thermal instability of PVA and oxygen chemistry present in the early beginning of the CVD growth. An optimized seeding process based on the polymer composite procedure at low substrate temperature and low PVA amount allows the diamond growth on extremely soft substrates. [source]