In order to determine which region was the major source of the dislocations which will be present in an LEC grown InP single crystal, a model of dislocation generation in InP was designed and numerically solved in the actual growth parameters and geometry. The Haasen model of dislocation generation was improved by projection of the mechanical stresses on the glide planes. This permits to take independently into account the interaction of dislocations situated in the same plane and in different planes (following works by Sumino). An important mechanism, acting principally at high temperatures, was the annihilation of dislocations by pairs. In the proposed model, the associated decrease of dislocation density was proportional to the square of the density of dislocations and of their velocity. The model was solved numerically with the help of the finite element software MARC®. It was validated by comparison with deformation tests at high temperature and the annihilation mechanism permits to explain the fully plastic behaviour of InP above 1250K. In a second step, this numerical model was interfaced with a global fully time-dependent modeling of heat transfer in the furnace. The model was adjusted by fitting the coefficient of dislocation annihilation in order to get the experimental number of dislocations in the first wafer of the reference crystal. The evolution of dislocation density with time, for a given location in the crystal, could therefore be predicted and was in good agreement, axially and radially, with experimental results. It was shown that dislocations situated in the center of the crystal were generated close to the solid–liquid interface and that peripheral dislocations, which were the most detrimental, were generated at the surface of the encapsulant.

A Visco-Plastic Model of the Deformation of InP during LEC Growth Taking into Account Dislocation Annihilation. S.Gondet, T.Duffar, F.Louchet, F.Theodore, N.Van Den Bogaert, J.L.Santailler: Journal of Crystal Growth, 2003, 252[1-3], 92-101