Thickness-dependent nonlinear absorption behaviors in polycrystalline ZnSe thin films

Karatay A., Yaglioglu H. G., Elmali A., PARLAK M., KARAAĞAÇ H.

OPTICS COMMUNICATIONS, cilt.285, sa.6, ss.1471-1475, 2012 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 285 Sayı: 6
  • Basım Tarihi: 2012
  • Doi Numarası: 10.1016/j.optcom.2011.11.088
  • Dergi Adı: OPTICS COMMUNICATIONS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.1471-1475
  • Anahtar Kelimeler: Semiconductor, Z-scan, Nonlinear absorption, Saturable absorption, Two photon absorption, OPTICAL-PROPERTIES, DEVICES, EDGE
  • Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

Polycrystalline ZnSe thin films have been deposited with different thicknesses by using sputtering evaporation method. Their nonlinear absorption behaviors were investigated by open aperture Z-scan and pump-probe techniques. Linear absorption measurements show redshift in energy as the film thickness increases. This can be attributed to Urbach tail effect. All films exhibit nonlinear absorption for 65 ps pulse duration at lower input intensities while they exhibit saturable absorption at higher input intensities. The life time of localized defect states on grain boundary was found to be similar to 3 ns from ultrafast pump-probe spectroscopy. Nonlinear absorption coefficients and saturation intensity thresholds were extracted from the fitting of the experimental data for 65 ps pulse duration. They increase with increasing film thickness. This behavior can be attributed to the increasing localized defect states on grain boundaries as the film thickness increases. (C) 2011 Elsevier B.V. All rights reserved.