Evolution of structural disorder in amorphous GeSeS thin films by thickness variation

R. T.Ananth Kumar, Naser N. Qamhieh, Saleh T. Mahmoud, P. Chithra Lekha, K. Jeyadheepan, C. Sanjeeviraja, D. Pathinettam Padiyan

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Amorphous GeSeS thin films are deposited for five different thicknesses using thermal evaporation technique and their microstructures are analyzed. The oscillations obtained in the optical transmittance spectra are resulted from the interference between the air-film and film-substrate interfaces. The observed decrease in the optical band gap with increase in the thickness of the film is associated with the change in the bonds formed in the structure of the network. Structural disorder like unsaturated bonds (dangling bonds) are studied by means of Tauc parameter (B1/2), Urbach energy (EU), and thermal diffusivity. The formation of heteropolar bonds become enormous for higher thickness of GeSeS thin films. From Raman spectra the bonds associated with symmetric stretching and tetrahedral units are discussed. Phonon-phonon scattering is the dominating mechanism which determines the phonon mean free path and hence the measured variation in thermal diffusivity.

Original languageEnglish
Pages (from-to)135-140
Number of pages6
JournalJournal of Non-Crystalline Solids
Publication statusPublished - Oct 15 2016


  • Chalcogenide glasses
  • Raman spectra
  • Thermal diffusivity
  • Urbach energy
  • Vacuum deposition

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Materials Chemistry


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