Close-to-Dirac point shift of large-area MOCVD-grown Bi₂Te₃’s Fermi level following growth on Sb₂Te₃

We developed a Metal Organic Chemical Vapour Deposition (MOCVD) process to grow the bi-layered Bi₂Te₃(top)/Sb₂Te₃ topological insulator on top of 4’’ Si(111). In single-phase Bi₂Te₃/Si(111), we have previously demonstrated clear topologically-protected surface states (TSS) by angle-resolved photoemission spectroscopy (ARPES) and magnetotransport, but a strong bulk contribution was still present with the Fermi level (E_F) crossing the conduction band at ~0.5 eV above the Dirac point [1]. Following the growth of 90 nm Bi₂Te₃ in direct contact with 30 nm Sb₂Te₃, we observed by ARPES a remarkable shift of E_F towards the Dirac point, totally suppressing the bulk states’ contribution. This was confirmed by magnetotransport, where, within the Hikami-Larkin-Nagaoka model, we measured an ideal α=-0.5 due to the optimized topologically-protected surface states. We will also present the first attempts in making use of such close-to-ideal positioning of the Bi₂Te₃’s Fermi level to manipulate magnetic figures in 2D-ferromagnet CrTe₂ grown on top of the developed Bi₂Te₃/Sb₂Te₃/Si(111) heterostructure.

[1] L. Locatelli, A. Kumar, P. Tsipas, A. Dimoulas, E. Longo, R. Mantovan, "Magnetotransport and ARPES studies of the topological insulators Sb₂Te₃ and Bi₂Te₃ grown by MOCVD on large-area Si substrates" Scientific Reports 12, 3891 (2022).