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RESEARCH PRODUCT

Numerical analysis of the influence of ultrasonic vibration on crystallization processes

B. UbbenjansBernard NackeJanis VirbulisCh. Frank-rotschPeter Rudolph

subject

Materials scienceCrucibleGeneral ChemistryMechanicsCondensed Matter Physicslaw.inventionDiffusion layerlawFluid dynamicsFluentGeneral Materials ScienceUltrasonic sensorCrystallizationDisplacement (fluid)Melt flow index

description

The challenge in the future fabrication of semiconductor bulk crystals is the improvement of the crystal quality with a simultaneous increase of the yield. For that, a proper control of mass transfer within the fluid phase is required. Besides the damping of violent convective fluctuations, the thickness of the diffusion boundary layer, causing morphological instability, has to be decreased. The influence of ultrasound in molten Germanium was analyzed by numerical simulations. The simulations were provided by applying commercial software packages ANSYS ® and FLUENT ® . ANSYS ® was used to model the ultrasonic wave propagation in the whole growth system consisting of melt and crystal, crucible and surrounding media. As a result the sound pressure distribution in every point of the melt and the displacement in every point of the solid have been obtained. The melt flow and the temperature distribution were simulated with the help of FLUENT ® . The main focus was the analysis of Schlichting streams that occur at the crystallization front which affect the diffusion boundary layer. It was shown that ultrasonic treatment can help to reduce the harmful diffusion boundary layer very effectively.

yearjournalcountryeditionlanguage
2011-10-06Crystal Research and Technology
https://doi.org/10.1002/crat.201100413