an apparatus for substantially eliminating excessive edge growth in liquid phase epitaxy utilizing a substrate carrier 11 and a source material carrier 13 slidable over the substrate carrier 11 including a well 24 around a recess 14 in the substrate carrier 11 wherein the substrate 16 is held . the well 24 contains a material therein which reduces the heat loss from the edges of the substrate 16 held in the recess 14 thereby reducing excessive epitaxial growth around the edges of the substrate 16 .