P–N Junctions in Ultrathin Topological Insulator Sb₂Te₃/Bi₂Te₃ Heterostructures Grown by Molecular Beam Epitaxy

Abstract

We fabricated topological insulating Sb2Te3/Bi2Te3 p–n heterostructures by means of molecular beam epitaxy and characterized the topography of the films by scanning tunneling microscopy. Due to the van der Waals growth mode of the layered Te compounds, X-ray diffraction measurements show that the heterostructure is fully relaxed on the Si(111) substrate. Furthermore, scanning transmission electron microscopy measurements unveil the crystalline structure of the p–n interface. Energy dispersive X-ray spectroscopy and atom probe tomography enable the mapping of the chemical element distribution. We conclude that a diffusion of Sb and Bi during growth causes the formation of ternary compounds. In addition a Sb and Te accumulation at the substrate interface could be detected. Transport measurements prove the tunability of the carrier concentration via thickness variation of the p–n heterostructure.

Topological Insulator Film Growth by Molecular Beam Epitaxy: A Review

“…ARPES data revealed that Dirac cone surface states still exist at the surface of Sb2Te3. Another group also reported Sb2Te3/Bi2Te3 heterostructures grown on Si(111) [125]. They found that ternary compounds formed at the interfaces due to Sb/Bi diffusion between layers.…”

“…In addition to growing ternary alloys, topological insulator p-n junctions have also been grown, typically using the binary compounds [125]. They found that ternary compounds formed at the interfaces due to Sb/Bi diffusion between layers.…”

Phase change thin films for non-volatile memory applications

“…This passivation layer is formed during the initial stages of deposition followed by the emergence of a vdW gap bridge from the passivation layer to the rst Te layer of the growing GST thin lm. 78,112,113 Consequently, only weak interactions between the substrate and thin lm are present enabling almost strain-free epitaxy. The strain energy between the substrate and thin lm is released rst by introduction of mist dislocation into the passivation layer and second by slight in-plane rotation of GST grains due to domainmatched epitaxy (Fig.…”

Rare Earth Doping of Topological Insulators: A Brief Review of Thin Film and Heterostructure Systems

“…Even more suited than ferromagnetic insulators, however, are other MTIs with higher transition temperatures, such as Cr doped Sb 2 Te 3 , with TC 's of 125 K for x = 0.42 and 190 K for x = 0.59, which is approximately linearly increasing with Cr doping . This combination of TIs in the form of Bi 2 Te 3 /Sb 2 Te 3 heterostructures preserves the TSS and simplifies the growth greatly due to the similar structural properties, effectively generating a hybrid TI system with higher order temperature and high magnetic moments …”