InP synthesis by the synthesis, solute diffusion (SSD) method using glassy-carbon crucibles

An InP synthesis system for the synthesis, solute diffusion (SSD) method has been built. It provides high purity InP charges with low carrier densities to be used as starting material for single-crystal liquid encapsulated Czochralski (LEC) growth. The synthesis is usually performed in quartz crucibles but as the silica walls react with the In-P solution, the crucible breaks during the furnace cooling at the end of the process. Also, the purity of crystals grown in a silica crucible is reduced due to Si contamination, since the dominant donor impurity in SSD grown InP has been identified as Si. Glassy-carbon is a refactory material with low vapor pressure that can be moulded in various forms and sizes. Indeed the glassy-carbon crucible is reusable after the synthesis because InP does not stick to its walls. Preliminary electrical characteristics measurements showed a residual carrier concentration below 3x10¹⁵ cm^-3. This result is comparable with those achieved utilizing quartz crucibles. These features make glassy-carbon an interesting alternative in comparison with quartz and PBN crucibles