Electronic properties of ultrathin Bi₂Te₃ films grown on CaF₂(111)

Abstract

We have studied the electronic structure and electrical conduction of ultrathin Bi₂Te₃ films grown on CaF₂(111)/Si(111) by molecular beam epitaxy. Angle-resolved photoelectron spectroscopy (ARPES) showed that the electronic structure of the films near the Fermi level consists of a surface band and a conduction band. Sheet electrical conductivity of the films was measured by a home-built UHV-compatible four-point probe. Residual conductivity σ₀ measured at 10 K showed a rapid increase above three quintuple layer (QL). ARPES and low-energy electron diffraction (LEED) results indicate that the thickness dependence in σ₀ is mainly attributed to the improvement of crystal quality of the films.