A Study of Convection,Striations and Interface Shape in InP Crystals Grown by the Double-Crucible LEC Technique

A doublecrucible (DC) Czochralski setup has been used for the pulling of semi-insulating Fe-doped InP. The level of the Fe-doped melt in the growth crucible is replanished with the undoped InP from the reservoir crucible. In this way, since the distribution coefficient of iron is very small (about 0.001), the Fe concentration in the growth crucible is virtually unchanged during the pulling so that the axial Fe concentration is much more uniform than in standard LEC crystals. The use of two concentric crucibles has great implications in terms of convective flows, stability of the melt temperature and interface shape. In this paper we report the results of a study on striations and structural defects in InP grown from a double-crucible LEC arrangement. A dimensionless relationship for correlating striation features with melt motions is also proposed.