Molecular-beam epitaxy of Sb₂Te₃-based alloys via metallic nucleation layers

Sb₂Te₃-based alloys are emerging two-dimensional (2D) materials that provide novel quantum states for faster and more efficient information processing.  It has been suggested that wafer-scale integration of 2D materials may be facilitated by metallic nucleation layers that promote remote epitaxy [1].  For example, Sb₂Te₃-based films have been grown epitaxially on substrates ranging from glass to sapphire [2]. Here, we explore the nucleation and growth of Sb₂Te₃-based films on sapphire substrates using metallic nucleation layers. For example, nucleation layers consisting of antimonene monolayers, with honeycomb structures similar to those of graphene, facilitate subsequent epitaxy of 19 to 30 quintuple layers of (Bi_xSb_1-x)₂Te₃ with exceptional transport properties.  We consider the roles of Sb₂Te₃ flux, substrate temperature, and negative surface charging (from reflection high energy electron diffraction) on nucleation layer formation and molecular-beam epitaxy of Sb₂Te₃-based alloys.  We will also discuss the influence of the metallic interlayer domain sizes and orientations on the formation of twin boundaries within Sb₂Te₃-based thin films.

[1] Science 390, 6771, (2025) DOI: 10.1126/science.aea0849

[2] Appl. Phys. Lett. 105, 221606 (2014) DOI: 10.1063/1.4903268