Magnetotransport and ARPES studies of the topological insulators Sb2Te3 and Bi2Te3 grown by MOCVD on large-area Si substrates

Abstract

Recently, the topological insulators (TIs) antimony telluride (Sb₂Te₃) and bismuth telluride (Bi₂Te₃) are attracting high interest for applications based on spin-charge interconversion mechanisms. Aiming to make a step toward the technology transfer, it is of major importance to achieve and investigate epitaxial quality-TIs on large area Si-based substrates. In view of that, we report here magnetotransport and angle-resolved photoemission spectroscopy (ARPES) studies on Sb₂Te₃ and Bi₂Te₃ thin films grown by metal organic chemical vapor deposition (MOCVD) on top of 4″ Si(111) substrates. Clear weak antilocalization (WAL) effects are observed in both TIs, proving the existence of quantum transport mechanism, and the data are successfully interpreted in the framework of the Hikami–Larkin–Nagaoka model. Further, by dedicated magnetotransport experiments, it has been confirmed that the investigated WAL originates from two-dimensional (2D) topological states. ARPES has been performed ex-situ, and in both TIs the gapless Dirac cones have been observed and attributed to the topological surface states. Combining the proofs of the existence of quantum 2D transport as deduced from the analysis of the magnetoconductance curve with the direct observation of the Dirac-like band structure revealed by the ARPES spectra, it is possible to unambiguously confirm the topological nature of our Sb₂Te₃ and Bi₂Te₃ thin films. The results obtained on thin films grown by MOCVD on 4’’ Si(111) substrate mark an important step towards the technology transfer of the topological insulators studied in this work.