Comparison of growth characteristics of sapphire and silicon ribbon produced by EFG

Abstract

Finite element analysis of heat transfer and meniscus shape is used to compare the operating conditions for Edge-defined Film-fed Growth (EFG) of silicon and sapphire (Al2O3) sheets. The relationships between sheet thickness and growth velocity are predicted for both systems with varying ambient thermal conditions. More effective radiative heat transfer between the melt and surroundings makes the Al2O3 growth less sensitive to growth rate variations and leads to more comvex (with respect to the melt) melt/solid interface shapes than for Si sheets grown from a die with the same dimensions. Considering capillarity alone would lead to the opposite conclusion for the sensitivity of sheet thickness to growth rate.