Possible flat band bending of the Bi1.5Sb0.5Te1.7Se1.3crystal cleaved in an ambient air probed by terahertz emission spectroscopy.
We investigate an evolution of the surface electronic state of the Bi1.5Sb0.5Te1.7Se1.3single crystal, which is one of the most bulk insulating topological insulators, by examining terahertz light emitted from the sample surface upon the illumination of the near-infrared femtosecond laser pulses. We find that the surface state with a flat band bending can appear in the course of the natural maturation process of the surface state in an ambient air. Furthermore, we demonstrate that the evolution of the surface electronic state can be accelerated, decelerated, or even stopped by controlling environmental conditions to contain different amount of H2O, in particular.
Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea.
Soon Hee
SH
Park
Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea.
Sun Young
SY
Hamh
Department of Physics, Pohang University of Science and Technology, Pohang 37673, Republic of Korea.
Joonbum
J
Park
Department of Physics, Pohang University of Science and Technology, Pohang 37673, Republic of Korea.
Jun Sung
JS
Kim
Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea.
Jong Seok
JS
Lee