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 (EF) 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 EF 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). *We acknowledge the Horizon 2020 project SKYTOP "Skyrmion-Topological Insulator and Weyl Semimetal Technology" (FETPROACT-2018-01, n. 824123).