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Topological insulators are a new class of semiconductor exhibiting charge-gapped insulating behavior in the bulk, but hosting a metallic Dirac electron state at the surface. Owing to the Dirac surface state as same as graphene, topological insulator gets much attention for applying to low-power consumption electronic devices.
Researchers at Department of Applied Physics, the University of Tokyo, headed by Professor Yoshinori Tokura, in collaboration with PhD candidate Ryutaro Yoshimi and the members in RIKEN CEMS, have demonstrated that the Dirac state of topological insulator is stably-formed at the solid-state interface, which was electrically detected by the tunneling spectroscopy across the interface between a topological insulator  ((Bi 1-xSb x) 2Te 3) and a conventional semiconductor (InP). In addition, the Dirac states in the junction device are well controlled by the composition of topological insulators. These achievements reveal the possibility of new functional devices based on topological insulators combined to the conventional semiconductor technologies. This research was supported by the Japan Society for the Promotion of Science through the Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST Program) on “Quantum Science on Strong Correlation” initiated by the Council for Science and Technology Policy and by JSPS Grant-in-Aid for Scientific Research(S) No. 24224009 and No. 24226002.