Self-assembled nano-columns in Bi2Se3 grown by molecular beam epitaxy

TL;DR

This paper reports the discovery of self-assembled nano-column structures in Bi2Se3 thin films grown on GaAs substrates via molecular beam epitaxy, challenging the typical weak substrate interaction assumption for vdW materials.

Contribution

It demonstrates that Bi2Se3 can form nano-column morphologies due to strong substrate interaction, long adatom diffusion, and high selenium flux, enabling self-assembly without strain.

Findings

Bi2Se3 forms nano-columns on GaAs(001) substrates.

Strong film/substrate interaction influences morphology.

Self-assembly occurs without strain in vdW materials.

Abstract

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.