Revisiting the van der Waals Epitaxy in the Case of (Bi(0.4)Sb(0.6))(2)Te(3) Thin Films on Dissimilar Substrates

Ultrathin films of the ternary topological insulator (Bi [Formula: see text] Sb [Formula: see text]) [Formula: see text] Te [Formula: see text] are fabricated by molecular beam epitaxy. Although it is generally assumed that the ternary topological insulator tellurides grow by van der Waals epitaxy, our results show that the influence of the substrate is substantial and governs the formation of defects, mosaicity, and twin domains. For this comparative study, InP (111)A, Al [Formula: see text] O [Formula: see text] (001), and SrTiO [Formula: see text] (111) substrates were selected. While the films deposited on lattice-matched InP (111)A show van der Waals epitaxial relations, our results point to a quasi-van der Waals epitaxy for the films grown on substrates with a larger lattice mismatch.