Composition-dependent topological-insulator properties of epitaxial (Bi1-xSbx)2(Te1-ySey)3 thin films

• Published in: Journal of alloys and compounds 2019-09, Vol.800, p.81-87
• Main Authors: Lee, Milim, Cho, Seong Won, Yi, Yeonjin, Lee, Suyoun
• Format: Article
• Language: English
• Subjects: (Bi1-xSbx)2(Te1-ySey)3; Bulk density; Carrier density; Carrier transport; Composition effects; Electronic devices; Spin-orbit coupling; Spin-orbit interactions; Suppression of bulk conductivity; Thin films; Topological insulator; Topological insulators; Topology
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.05.351

Due to strong spin-orbit coupling (SOC), topological insulators (TIs) have attracted much interest in developing novel energy-efficient electronic devices. (Bi1-xSbx)2(Te1-ySey)3 (BSTS) has been regarded as a prototypical TI because of the dominance of the surface channel in carrier transport. Nevertheless, the effect of the composition of BSTS on SOC has not been explored, which is important for the application in novel electronic devices. In this work, BSTS thin films with systematically varying compositions are examined to release composition-dependent maps for the bulk carrier density, the dominance of the surface states in carrier transport, and the strength of SOC. The maps show that the regions for optimizing each property are located in separate positions, with a narrow overlap between them. These results imply that a stringent control in composition of the BSTS thin film is required in order to take advantage of the spin-momentum-locked surface channel of TI in novel electronic devices. •(Bi1-xSbx)2(Te1-ySey)3 epitaxial thin films with varying composition are grown.•The composition area is specified where surface-dominant transport is shown.•Composition-dependent map of the bulk (σb) and surface (σs) conductivity is disclosed.•Composition-dependent map of spin-orbit coupling strength is disclosed.•Stringent composition control is required for strong SOC and low σb simultaneously.