TY - JOUR

T1 - Raman scattering spectroscopy of MBE grown thin film topological insulator Bi2−xSbxTe3−ySey

AU - Kumar, Niranjan

AU - Surovtsev, N. V.

AU - Yunin, P. A.

AU - Ishchenko, D. V.

AU - Milekhin, I. A.

AU - Lebedev, S. P.

AU - Lebedev, A. A.

AU - Tereshchenko, O. E.

N1 - The authors acknowledge support from the Russian Science Foundation (Grant No. 22-12-20024, p-9), SRF SKIF Boreskov Institute of Catalysis (FWUR-2024-0042), IAiE SB RAS (FWNG-2024-0023) and ISP SB RAS. The work was partly supported by the Ministry of Science and Higher Education of the Russian Federation (Project 075-15-2021-1349). The authors also acknowledge the shared-user facility \u201CNanostructures\u201D in the ISP Center for the provision of experimental equipment.

PY - 2024/4/12

Y1 - 2024/4/12

N2 - BSTS epitaxial thin film topological insulators were grown using the MBE technique on two different types of substrates i.e., Si (111) and SiC/graphene with Bi0.7Sb1.6Te1.8Se0.9 and Bi0.9Sb1.5Te1.8Se1.1, respectively. The crystallographic properties of BSTS films were investigated via X-ray diffraction, which showed the strongest reflections from the (0 0 l) facets corresponding to the rhombohedral phase. Superior epitaxial growth, homogeneous thickness, smooth surfaces, and larger unit cell parameters were observed for the films grown on the Si substrate. Polarization dependent Raman spectroscopy showed a weak appearance of the Ag mode in cross-polarized geometry. In contrast, a strong Eg mode was observed in both parallel and cross-polarized geometries which correspond to the rhombohedral crystal symmetry of BSTS films. A redshift of Ag and Eg modes was observed in the Raman spectra of BSTS films grown on the Si substrate, compared to those on SiC/graphene, which was directly associated with the unit cell parameter and composition of the films. Raman spectra showed four fundamental modes with asymmetric line shape, and deconvolution of the peaks resulted in additional modes in both the BSTS thin films. The sum of relative ratios of linewidths of fundamental modes (Ag and Eg) of BSTS films grown on Si substrate was lower, indicating a more ordered structure with lower contribution of defects as compared to BSTS film grown on SiC/graphene substrate.

AB - BSTS epitaxial thin film topological insulators were grown using the MBE technique on two different types of substrates i.e., Si (111) and SiC/graphene with Bi0.7Sb1.6Te1.8Se0.9 and Bi0.9Sb1.5Te1.8Se1.1, respectively. The crystallographic properties of BSTS films were investigated via X-ray diffraction, which showed the strongest reflections from the (0 0 l) facets corresponding to the rhombohedral phase. Superior epitaxial growth, homogeneous thickness, smooth surfaces, and larger unit cell parameters were observed for the films grown on the Si substrate. Polarization dependent Raman spectroscopy showed a weak appearance of the Ag mode in cross-polarized geometry. In contrast, a strong Eg mode was observed in both parallel and cross-polarized geometries which correspond to the rhombohedral crystal symmetry of BSTS films. A redshift of Ag and Eg modes was observed in the Raman spectra of BSTS films grown on the Si substrate, compared to those on SiC/graphene, which was directly associated with the unit cell parameter and composition of the films. Raman spectra showed four fundamental modes with asymmetric line shape, and deconvolution of the peaks resulted in additional modes in both the BSTS thin films. The sum of relative ratios of linewidths of fundamental modes (Ag and Eg) of BSTS films grown on Si substrate was lower, indicating a more ordered structure with lower contribution of defects as compared to BSTS film grown on SiC/graphene substrate.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85190973019&origin=inward&txGid=91c9371d9cef8df4d0d89491494a03ea

UR - https://www.mendeley.com/catalogue/6e71fd72-7fcd-3794-ba66-bd92c02d014a/

U2 - 10.1039/d4cp01169d

DO - 10.1039/d4cp01169d

M3 - Article

C2 - 38651229

VL - 26

SP - 13497

EP - 13505

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 17

ER -