Evidence of twin mediated growth in the CVD of polycrystalline silicon carbide

International audience ; The origin of the <110> texture in polycrystalline 3C-SiC grown by chemical vapor deposition at different temperatures is investigated by thorough EBSD, SEM and XRD characterizations. Regarding the <110> orientation, although XRD suggests a fiber texture, closer inspection of isolated clusters of grains by EBSD reveals a high symmetrical order in-plane. The pole figures associated with these clusters are in good agreement with cross-twinned pentagonal structures in which each grain shares a common <110> axis. These structures form via twin-mediated growth involving the formation of twin plane reentrant edges that act as a preferential site for the incorporation of adatoms. A deviation from a perfect cross-twinned structure is observed and is attributed to the presence of additional parallel twins. In this study, the transition to the <110> orientation occurs when the temperature increases and the partial pressure of reactive species decreases. This can be explained by the enhancement of surface mobility that promotes surface diffusion to the twin plane reentrant edges, thus activating the twin mediated growth mechanism.