Electronic structure of Bi2X3 (X=S, Se, T) compounds: Comparison of theoretical calculations with photoemission studies
In recent years electronic structures of Bi2Te3 and related materials have been studied theoretically through ab initio band-structure calculations and experimentally through photoemission experiments, but to the best of our knowledge, a detailed comparison between experiment and theory has not been attempted so far. In this paper we discuss the density of states (DOS) of the narrow-gap semiconductors Bi2X3 (X=S, Se, Te) obtained within density-functional theory. While several electronic structure calculations for Bi2Te3 and Bi2Se3 have been reported in the literature, there have been no published calculations for Bi2S3 or Bi2Te2Se. Recent photoemission and inverse-photoemission measurements in these systems, performed by four separate groups (including our photoemission measurements of Bi2Te3 and Bi2Se3), allows for a comparison of the general features of the calculated DOS for both valence- and conduction-band states with photoemission and inverse-photoemission spectra. The agreement between the positions of the prominent peaks in the calculated DOS and photoemission spectra continues to improve with better energy resolution in the experiment.