  Layered van der Waals (vdW) materials grown by physical vapor deposition
techniques are generally assumed to have a weak interaction with the substrate
during growth. This leads to films with relatively small domains that are
usually triangular and a terraced morphology. In this paper, we demonstrate
that Bi2Se3, a prototypical vdW material, will form a nano-column morphology
when grown on GaAs(001) substrates. This morphology is explained by a
relatively strong film/substrate interaction, long adatom diffusion lengths,
and a high reactive selenium flux. This discovery paves the way toward growth
of self-assembled vdW structures even in the absence of strain.
