Faceting Simulation of Bulk Crystal Growth with 2d Nucleation and Screw Dislocation Theory

During directional solidification of semiconductor or oxide crystals, the appearance of facets along the meltcrystal interface is a common phenomenon with scientific and practical importance. In this paper, the computational simulation of faceting is carried out for Bridgman growth of YAG crystals. The mathematical models consider the coupling between kinetic undercooling and melt convection and thermal transport. Both the screw dislocation and the twodimensional nucleation theory are used, for facets with and without growth spirals, respectively. A linear relation between the growth velocity and undercooling is applied to atomic rough surfaces. The interface location is tracked, so as to record an initial timedependent evolution of the facet towards its timeindependent shape. The differences among the different growth theory are compared and discussed, and the effects of the undercooling coefficients on transient features during facet formation are also investigated.