Spectroscopic ellipsometry study of Bi12TiO20 single crystals


Isik M., Hasanlı N., Darvishov N. H. , Bagiev V. E.

JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS, vol.32, no.6, pp.7019-7025, 2021 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 32 Issue: 6
  • Publication Date: 2021
  • Doi Number: 10.1007/s10854-021-05411-w
  • Journal Name: JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aerospace Database, Applied Science & Technology Source, Chemical Abstracts Core, Communication Abstracts, Compendex, Computer & Applied Sciences, INSPEC, Metadex, Civil Engineering Abstracts
  • Page Numbers: pp.7019-7025
  • Middle East Technical University Affiliated: Yes

Abstract

Bi12XO20 (X: Si, Ge, Ti, etc.) ternary compounds have attracted attention especially due to their fascinating photorefractive characteristics. The present paper introduces the structural and optical characteristics of Bi12TiO20 single crystals grown by Czochralski method. X-ray diffraction pattern of the compound exhibited sharp and intensive peaks corresponding to parallel planes of cubic crystalline structure. The lattice constant of the cubic structure was determined as a = 1.0118 nm using a diffraction pattern indexing program. The optical characterization of the Bi12TiO20 single crystals was carried through spectroscopic ellipsometry experiments performed in the 1.2-5.0 eV spectral range. The spectral dependencies of refractive index, extinction coefficient, and complex dielectric function were revealed analyzing experimental ellipsometric data under the light of sample-air optical model. The band gap energy of the compound was determined as 3.34 eV from the analyses of absorption coefficient. Three critical points at 3.51, 4.10, and 4.71 eV were obtained from the analyses of components of dielectric function using their second-energy derivative spectra.