1 research outputs found
Mode of Growth of Ultrathin Topological Insulator Bi<sub>2</sub>Te<sub>3</sub> Films on Si (111) Substrates
Layered materials such as graphene, bi-, and multilayer
graphene
as well as various compounds of topological insulators are currently
in the focus of interest due to their extraordinary physical properties
related to Dirac surface states. The ability to grow thin films of
these complex layered materials is the key to explore their fundamental
phenomena giving insights into modern solid-state physics. However,
complex materials composed of layers only weakly bonded via van der
Waals forces offer unmatched challenges for the deposition of thin
epitaxial films. Here, we report on the growth of Bi<sub>2</sub>Te<sub>3</sub> ultrathin films on Si (111) substrates using molecular beam epitaxy. Special emphasis is put
on the nucleation phenomena and growth dynamics studied in detail
by in situ scanning tunnelling microscopy and high-resolution scanning
transmission electron microscopy. The morphology of the Bi<sub>2</sub>Te<sub>3</sub> surface and the structure of the Si(111)/Bi<sub>2</sub>Te<sub>3</sub> interface as well as the formation of threading dislocations
and crystal domains are studied at the atomic level. Our data indicate
that the film is formed via the nucleation of islands, which float
on the substrate; thus, the islands are only weakly bonded to the
substrate and rather mobile. Apparently, these floating islands are
able to arrange themselves by moving in the <i>x</i>–<i>y</i> direction to perfectly coalesce and form a continuous
film. The results present a crucial step toward understanding growth
and defect formation in this class of materials and thus pave the
avenue to a higher control over both their structural and electronic
properties, in order to study the electronic properties of the Dirac
surface states