Kinetic faceting of multiply twinned diamond crystals during vapor phase synthesis

摘要

Multiply twinned particles in diamond cubic crystals such as decahedron and icosahedron were explained using Kinetic Monte Carlo (KMC) simulations by the sequential occurrence of two and three stacking faults on different [111] surfaces during vapor-phase growth. However, the same simulations, using single adapton adsorption and desorption of singly bonded sites, failed to predict the kinetic faceting of another commonly observed 'star-shaped' decahedron. In this work, a set of KMC simulations were performed using an additional reaction step for etching of doubly bonded surface sites during growth starting with a seed crystal containing two stacking errors. These simulations produced star-shaped decahedral crystals and thus pointed to a possible explanation of the observed 'star-shaped' decahedral morphology for diamond crystals. The experimental results on the morphological evolution of star-decahedral crystals exhibited a sequence in which an intermediate shape, between decahedron and icosahedron, developed into a more complete icosahedral shape upon further growth.