Spin-orbit interaction effect in the electronic structure of Bi₂Te₃ observed by angle-resolved photoemission spectroscopy

¹  Department of Physics, Chonnam National University - Gwangju 500-757, Korea
²  School of Physics & Center for Strongly Correlated Materials Research, Seoul National University Seoul 151-742, Korea
³  Department of Physics, Pohang University of Science and Technology - Pohang 790-784, Korea
⁴  Pohang Accelerator Laboratory, Pohang University of Science and Technology - Pohang 790-784, Korea
⁵  Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory Upton, NY 11973, USA
⁶  Department of Physics & Astronomy, Stony Brook University - Stony Brook, NY 11974, USA

Corresponding author: ffnhj@chonnam.ac.kr

Received: 23 October 2007
Accepted: 14 January 2008

Abstract

The electronic structure of p-type doped Bi₂Te₃ is studied by angle-resolved photoemission spectroscopy (ARPES) to experimentally confirm the mechanism responsible for the high thermoelectric figure of merit. Our ARPES study shows that the band edges are located off the -Z line in the Brillouin zone, which provides direct observation that the spin-orbit interaction is a key factor to understand the electronic structure and the corresponding thermoelectric properties of Bi₂Te₃. A successive time-dependent ARPES measurement also reveals that the electron-like bands crossing E_F near the -point are formed in an hour after cleaving the crystals. We interpret these as surface states induced by surface band bending, possibly due to quintuple inter-layer distance change of Bi₂Te₃.