Influence of thermal phenomena on crystal reattachment during dewetted Bridgman growth

On favorable thermal fields for detached Bridgman growth

“…A more robust approach is the tailoring of thermal conditions to coax the solidification isotherm to pass through the gap, under the meniscus, rather than through the melt, above the meniscus. Such conditions were shown in [14] to correspond with the promotion of convex solid-liquid interface shapes.…”

“…Our prior analysis employed a rigorous, thermal-capillary model that concentrated on the detailed coupling of interfacial and field phenomena but applied a very simplified representation of furnace heat transfer [14]. Here, we apply the sophisticated CrysMAS code developed by the Crystal Growth Laboratory of the Fraunhofer Institute of Integrated Systems and Device Technology (IISB) in Erlangen, Germany [15] to perform rigorous simulation of heat transfer in multi-zone Bridgman furnaces.…”

“…These detailed heat transfer computations are performed using the CrysMAS code and expand upon our previous analyses [14] that posited a new mechanism involving the thermal field and meniscus position to explain stable conditions for dewetted Bridgman growth. Computational results indicate that heat transfer conditions that led to successful detached growth in both of these systems are in accordance with our prior assertion, namely that the prevention of crystal reattachment to the crucible wall requires the avoidance of any undercooling of the melt meniscus during the growth run.…”

“…In a prior thermal-capillary analysis of detached Bridgman growth [14], we have put forth a new explanation for process stability that invokes heat transfer arguments to explain reattachment events that would end dewetting. According to our prior results, crystal reattachment to the crucible wall is explained by the freezing of the liquid meniscus between the growing crystal and the crucible wall, which occurs when the solidification isotherm passes above the liquid-gas surface of the meniscus.…”

“…The present work is meant to extend the understanding provided from our prior analysis [14] by focussing on thermal conditions associated with furnace design. We carry out detailed heat transfer computations for two configurations like those employed in prior experimental studies of the detached growth of germanium by Palosz et al [9] and cadmium telluride by Chevalier et al [5].…”