Structural, Optical, and Magnetic Properties of Solution-Processed Co-Doped ZnS Thin Films

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Goktas A., MUTLU İ. H.

JOURNAL OF ELECTRONIC MATERIALS, cilt.45, sa.11, ss.5709-5720, 2016 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 45 Sayı: 11
  • Basım Tarihi: 2016
  • Doi Numarası: 10.1007/s11664-016-4771-3
  • Dergi Adı: JOURNAL OF ELECTRONIC MATERIALS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.5709-5720
  • Anahtar Kelimeler: Co-doped ZnS, solution processing, photoluminescence, refractive index, dielectric constant, paramagnetic/ferromagnetic behavior, ROOM-TEMPERATURE FERROMAGNETISM, SOL-GEL, DEPENDENT ROOM, LUMINESCENCE, ZN1-XCOXS, SUSCEPTIBILITY, NANOPARTICLES, CATALYSTS, CELLS, FE
  • Akdeniz Üniversitesi Adresli: Evet

Özet

Co-doped ZnS thin films have been grown on glass substrates using solution-processing and dip-coating techniques, and the impact of the Co doping level (0% to 5%) and film thickness on certain characteristics examined. X-ray diffraction study revealed that all the films possessed hexagonal crystal structure. Energy-dispersive x-ray analysis confirmed presence of Zn, Co, and S in the samples. Scanning electron microscopy showed that the film surface was homogeneous and dense with some cracks and spots. X-ray photoelectron spectroscopy confirmed introduction and integration of Co2+ ions into the ZnS thin films. Compared with undoped ZnS, optical studies indicated a reduction in optical bandgap energy (E (g)) while the refractive index (n), extinction coefficient (k), and dielectric constants (epsilon (1), epsilon (2)) increased with film thickness (t) and Co doping level (except for 5%). Photoluminescence spectra showed enhanced luminescence intensity as the Co concentration was increased, while the dependence on t showed an initial increase followed by a decrease. The origin of the observed low-temperature (5 K and 100 K) ferromagnetic order may be related to point defects such as zinc vacancies, zinc interstitials, and sulfide vacancies or to the grain-boundary effect.

Co-doped ZnS thin films have been grown on glass substrates using solutionprocessing and dip-coating techniques, and the impact of the Co doping level (0% to 5%) and film thickness on certain characteristics examined. X-ray diffraction study revealed that all the films possessed hexagonal crystal structure. Energy-dispersive x-ray analysis confirmed presence of Zn, Co, and S in the samples. Scanning electron microscopy showed that the film surface was homogeneous and dense with some cracks and spots. X-ray photoelectron spectroscopy confirmed introduction and integration of Co2+ ions into the ZnS thin films. Compared with undoped ZnS, optical studies indicated a reduction in optical bandgap energy (Eg) while the refractive index (n), extinction coef- ficient (k), and dielectric constants (e1, e2) increased with film thickness (t) and Co doping level (except for 5%). Photoluminescence spectra showed enhanced luminescence intensity as the Co concentration was increased, while the dependence on t showed an initial increase followed by a decrease. The origin of the observed low-temperature (5 K and 100 K) ferromagnetic order may be related to point defects such as zinc vacancies, zinc interstitials, and sulfide vacancies or to the grain-boundary effect.