Spiral Growth of Bi₂Te₃ on GaAs(001) by Molecular Beam Epitaxy: Structural and Electronic Properties

The success of conventional epitaxial growth depends basically on the coherence between the lattice parameters of the film and the substrate, a condition known as lattice matching. This rule is difficult to follow since the availability of compatible substrates is small. To overcome this limitation, in recent years, epitaxial growth has been directed toward layered materials, in which the growth mechanism is given by van der Waals interaction. Bismuth telluride (Bi2Te3) is one such material which has recently been investigated as part of a new class of quantum materials with topological insulator (TI) properties. Although its growth on various substrates has been explored, systematic growth on GaAs, an important material for optoelectronic devices, has been poorly explored. In this work, the structural and electronic properties of the spiral growth mode of Bi2Te3 grown by molecular beam epitaxy on GaAs(001) were systematically investigated as a function of substrate temperature and film thickness. Atomic force microscopy, high-resolution X-ray diffraction, Raman spectroscopy, and scanning transmission electron microscopy were used to investigate the structural properties at the different stages of Bi2Te3 growth. Scanning tunneling microscopy and spectroscopy were used to probe the signatures of TI properties. Our findings provide valuable insights into the limitations and potential of van der Waals epitaxy, contributing to a deeper understanding of growth mechanisms of TI materials.