As a methodology for controlling the carrier transport of topological insulators (TIs), a flexible tuning in carrier number on the surface states (SSs) of three-dimensional TIs by surface modifications using organic molecules is described. The principle of the carrier tuning and its type conversion of TIs presented in this research are based on the charge transfer of holes or electrons at the TI-organic molecule interface. When 2,3,5,6-tetrafluoro-7,7,8, 8-tetracyanoquinodimethane (F4-TCNQ) as an electron acceptor or tetracyanoquinodimethane (TCNQ) as a donor is employed for n- and p-Bi 2-xSbxTe3-ySey (BSTS) single crystals, successful carrier conversion from n- to p-type and its reverse mode is demonstrated depending on the electron affinities of the molecules. The present method provides a nondestructive and efficient method for local tuning in carrier density of TIs and is useful for future applications.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films