Robustness of a Topologically Protected Surface State in a Sb2Te2Se Single Crystal

Abstract

A topological insulator (TI) is a quantum material in a new class with attractive properties for physical and technological applications. Here we derive the electronic structure of highly crystalline Sb2Te2Se single crystals studied with angle-resolved photoemission spectra. The result of band mapping reveals that the Sb2Te2Se compound behaves as a p-type semiconductor and has an isolated Dirac cone of a topological surface state, which is highly favored for spintronic and thermoelectric devices because of the dissipation-less surface state and the decreased scattering from bulk bands. More importantly, the topological surface state and doping level in Sb2Te2Se are difficult to alter for a cleaved surface exposed to air; the robustness of the topological surface state defined in our data indicates that this Sb2Te2Se compound has a great potential for future atmospheric applications.

Thickness-dependent conductance in Sb2SeTe2 topological insulator nanosheets

“…It is reported that the k F extracted from ARPES and SdH oscillation are different because of the sample inhomogeneity 25, 27 . Our ARPES and SdH oscillation show consistent results that support the high homogeneity of our samples 25, 26 . The k F deduces the surface density of state through the relation n s  =  k F 2 /4 π  = 4.95 × 10 12  cm −2 for a circular Fermi surface.…”

“…The observed SdH oscillation frequency, F  = 205 T, leads to k F  = 7.8 × 10 6  cm −1 , which is consistent with the value of k F  = 7.3 × 10 6  cm −1 extracted from ARPES from the different batches of the same crystal 26 . It is reported that the k F extracted from ARPES and SdH oscillation are different because of the sample inhomogeneity 25, 27 .…”

“…The SdH oscillation frequency, F , is directly related to the Fermi-level cross section via the Onsager relation , where k F is the Fermi vector, e is the electron charge and is the Planck constant. The observed SdH oscillation frequency, F = 205 T, leads to k F = 7.8 × 10 6 cm −1 , which is consistent with the value of k F = 7.3 × 10 6 cm −1 extracted from ARPES from the different batches of the same crystal 26 . It is reported that the k F extracted from ARPES and SdH oscillation are different because of the sample inhomogeneity 25 , 27 .…”

Highly responsive photoconductance in a Sb2SeTe2 topological insulator nanosheet at room temperature

“…[5][6][7] The theoretical calculation reveals that the Dirac point lies within the gap of the bulk state, 42 and our previous work supports the fact that the Fermi level lies below the Dirac point in our Sb 2 -SeTe 2 topological insulator. 26,43 This band structure of the Sb 2 -SeTe 2 topological insulator is similar to the graphene-TMD hybrid structure. The energy of the light at 325 nm is much larger than the band gap of the bulk state; thus, the photons can easily generate electron-hole pairs.…”

Extremely high-performance visible light photodetector in the Sb2SeTe2 nanoflake

“…The as-grown crystals were cleaved along the basal plane, producing a silvery shining mirror-like surface, and then prepared for the further experiments. The Raman27, EDS and XPS28 spectrum support that the crystal is Sb 2 SeTe 2 .…”