Optical properties of metal and semiconductor SmS thin films fabricated by rf/dc dual magnetron sputtering

S. Tanemura, L. Miao, S. Koide, Y. Mori, P. Jin, A. Terai, N. Nabatova-Gabain

Research output: Contribution to journalConference article

8 Citations (Scopus)

Abstract

Optical properties of both metal and semiconductor phases of SmS thin films on Si substrate grown at a room temperature by dual targets (dc for metal Sm and rf for pressed powdered chalcogenide Sm 2 S 3 ) magnetron sputtering system with the concurrent adjustment of the applied power to respective target, were evaluated by SE at the photon energy range between 0.75 to 5.0eV. This is the first work performed on the intrinsically prepared metallic sample while the former works done for the sample transformed from semiconductor to metal phase by hard polishing. The followings are concluded: (1) in the metallic film, the refractive indices n have maximum value of 2.20 at 4.10eV, while extinction coefficient k decreases monotonically and reaches 0.03 at 5.0eV. The absorption coefficient derived from the obtained k and the complex dielectric constant from n and k agree satisfactorily with those cited in the preceding literatures for the bulk samples; (2) in the case of semiconductor, the refractive indices n have the maximum 3.66 at 3.93eV, while extinction coefficient k increase monotonically from 0 at 2.31eV to 1.633 at 5.0eV. The optical transition mode from valence to conduction band is difficult to determine as either indirect allowed or direct forbidden mode because of the insignificant difference between the linear behavior of the curves α 1/2 and that of α 2/3 (α: absorption coefficient) as a function of photon energy beyond 3.5eV. Hence the optical band gap E g followed by indirect allowed mode and direct forbidden mode is given as 2.67 and 2.78eV, respectively. The agreement between the derived dielectric constant and those in the preceding literatures for bulk semiconductors is not satisfactory.

Original languageEnglish
Pages (from-to)360-366
Number of pages7
JournalApplied Surface Science
Volume238
Issue number1-4 SPEC. ISS.
DOIs
Publication statusPublished - 2004 Nov 15
Externally publishedYes
EventAPHYS 2003 - Badajoz, Spain
Duration: 2003 Oct 132003 Oct 18

Keywords

  • Complex refractive indices
  • Metallic phase
  • Semiconductor phase
  • SmS thin films
  • Spectroscopic ellipsometry

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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