Effect of thallium (Tl) substitution for indium (In) on ellipsometric characteristics of TlInSe2 single crystals


Isik M., HASANLI N.

Materials Science in Semiconductor Processing, vol.134, 2021 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 134
  • Publication Date: 2021
  • Doi Number: 10.1016/j.mssp.2021.106005
  • Title of Journal : Materials Science in Semiconductor Processing
  • Keywords: TlInSe2, Ellipsometry, Critical points, Optical properties

Abstract

© 2021 Elsevier LtdTlMeSe2 (Me: Tl, In) semiconducting compounds exhibiting chain structure have been attractive ternary materials in various technological devices. In the TlMeSe2 structure, Tl1+ is monovalent while Me3+ is trivalent ions. The present paper reports the results of spectroscopic ellipsometry measurements performed on Tl1+(Tl0.2In0.8)3+Se2 (abbreviated as Tl1.2In0.8Se2) single crystals which were grown by substituting thallium for indium. The measurements were performed for orientations of E//c and E丄c (E: electric field and c: optical axis). The analyses of ellipsometry data considering air-sample optical model presented the spectral dependencies of dielectric function, refractive index and extinction coefficient in the 1.2–5.0 eV range. Critical point energies of studied single crystal were obtained by fitting second-energy derivative spectra of dielectric function. The determined energies were compared with those of TlInSe2 to understand the effect of thallium-indium substitution in the compound. The crystal structure and atomic compositions of the constituent elements were also reported throughout the paper.