The formation of rotation domains (RDs) in heteroepitaxy depends fundamentally on the relation of the crystal symmetries of substrate and epilayer. We assume well-defined crystallographic axes of substrate and epilayer along the growth direction and determine from group theory the number of RDs with crystallographically equivalent interfaces (CEIF) for all combinations of the two-dimensional (2D) point symmetries of substrate and epilayer, including cases of aligned and misaligned symmetry directions. Additional domains can arise from multi-domain substrates. Accidentally or nearly fulfilled additional symmetries of the substrate allow further domains with crystallographically inequivalent interfaces (CIIF).
Schematic RDs for various rotation symmetries of substrate and epilayer.