Surface diffusion contribution to dendrite sidebranching during growth of 2D Kossel crystal from the vapor

A new microscopic model describing the transition of the growth habit from fingered to dendrite-branched is proposed. The transitions occur via sidebr anching creation, i.e. occurrence of the regions of faster and slower growt h on the finger sides. The dynamic criterion that controls dendrite sidebra nching is derived in terms of microscopic dynamic parameters for a two-dime nsional Kossel crystal. These form selection rules were compared to Monte C arlo (MC) atomic scale simulations of growth forms of Kossel crystal in 2D supersaturated vapor in a diffusive transport regime. The MC simulations we re used to show the interplay between supersaturation and surface free ener gy anisotropy in the selection of the shapes in the diffusion controlled gr owth. It has been demonstrated that the growth shape depends also on the su rface diffusion rate and the magnitude of surface free energy density. (C) 1999 Elsevier Science B.V. All rights reserved.