Modeling analysis of VCz growth of GaAs bulk crystals using 3D unsteady melt flow simulations

3D computations of melt convection and crystallization front geometry during VCz GaAs growth

“…It is remarkable that the simplest model without convective effects and with opaque encapsulant provides the best agreement with experimentally obtained interface geometry. However, it is well known that both convective effects [2,3,6] and radiative heat transfer through the encapsulant [4,5] are important physical mechanisms affecting the crystallization process. So, it would be proposed that the agreement between the particular experiment and the particular data by the effective conductivity model is more accidental than general.…”

“…In this approach, radiative heat exchange, conductive heat exchange and turbulent flows within the Reynolds-averaged Navier-Stokes (RANS) equations are considered in a conjugated way. Advanced analysis of heat transfer and melt/ encapsulant flows in the crystallization zone is performed within an updated 3D unsteady approach [6,7] based on the LES technique. The 3D analysis is applied to describe the real melt flow behavior, which is not always possible within the RANS approach usually resulting in steady-state axisymmetric flow patterns.…”

“…Material properties used for the analysis are the same as in Refs. [2,3,6]. The CGSim program package (see www.semitech.us/ products) based on the finite volume method has been used for the numerical analysis.…”

“…There are indications in the literature that semitransparent properties of the encapsulant are of influence on heat exchange near the melt-crystal region and should be therefore taken into account [4,5]. Recently, 3D unsteady calculations within the direct numerical simulation (DNS) approach [3] and using large eddy simulation (LES) [6,7] have been applied for analysis of melt convection during 3 00 GaAs single crystal growth in the LPA Mark 3, a commercial system modified for the VCz technique. However, it was found [6] that the experimental regimes with high crucible rotation rates are hard for numerical treatment because of strong velocity gradients.…”

“…Recently, 3D unsteady calculations within the direct numerical simulation (DNS) approach [3] and using large eddy simulation (LES) [6,7] have been applied for analysis of melt convection during 3 00 GaAs single crystal growth in the LPA Mark 3, a commercial system modified for the VCz technique. However, it was found [6] that the experimental regimes with high crucible rotation rates are hard for numerical treatment because of strong velocity gradients. No direct comparison between 3D calculations and experiments could be done so that the further development of a predictive model of crystallization during LEC and VCz growth remains to be of great importance.…”