Interface shape control using localized heating during Bridgman growth

Abstract

Numerical calculations were performed to assess the effect of localized radial heating on the melt-crystal interface shape during vertical Bridgman growth. System parameters examined include the ampoule, melt and crystal thermal conductivities, the magnitude and width of localized heating, and the latent heat of crystallization. Concave interface shapes, typical of semiconductor systems, could be flattened or made convex with localized heating. Although localized heating caused shallower thermal gradients ahead of the interface, the magnitude of the localized heating required for convexity was less than that which resulted in a thermal inversion ahead of the interface. A convex interface shape was most readily achieved with ampoules of lower thermal conductivity. Increasing melt convection tended to flatten the interface, but the amount of radial heating required to achieve a convex interface was essentially independent of the convection intensity.

GaAs Vertical Gradient Freeze Process Intensification

“…Therefore, the heat accumulates in front of the growing interface, promoting its concavity. Similar results were obtained for VB GaAs growth. , …”

“…Similar results were obtained for VB GaAs growth. 32,33 If the comparison is performed at the same moment of crystallization, an increase in GaAs load will cause an increase in axial temperature gradients and a decrease in growth rate. In practice, such a deceleration of the growth process is tackled by an adjustment of the cooling program.…”

Influence of the pulling rate on the properties of ZnGeP2 crystal grown by vertical Bridgman method

“…When the thermal stress is bigger than the CRSS, this means that more dislocations generate at the onset of grown crystal. Thus, a nearly fat solid/liquid interface is always preferred for the single crystal growth [32][33][34].…”

A method for flattening the solidification front in directional solidification technology

“…Jasinski et al [27] and Volz et al [28] stated that the interface shape can be improved using localized heating toward the interface during Bridgman process. However, a disadvantage in this method is that the axial temperature gradient is reduced as well.…”