Optical Properties of Copper and Silver Ion-Activated Films of a Cds–ZnS System, Deposited at Different Temperatures

Abstract

Purpose. In this study, the infl uence of the deposition temperature and of the impurities of
copper and silver ions (10–7–10–3 at. %) on the optical properties of fi lms of a CdS–ZnS system
was investigated.
Methods. The fi lms of a CdS–ZnS system were synthesized using the method of pyrolysis of the
aerosols of thiourea solutions of [М(N₂H₄CS)₂Br₂] (М = Cd, Zn) coordination compounds within the temperature range of 350–500 °С. The absorption and refl ection spectra were obtained in
the area of the fundamental absorption edge as the result of the study of fi lms of CdS–ZnS system
the optical properties. The phase composition and crystal structure of the fi lms were examined
using Х-ray diffraction analysis. The elemental composition of the samples was defi ned by the
method of local X-ray spectral microanalysis using a scanning electron microscope.
Results. The absorption and refl ection spectra of the CdS–ZnS fi lms doped with copper and
silver ions were studied and their optical band gap Eg was measured. It was found that an increase
in the amount of zinc sulphide in the samples results in progressive increase in the value of the
optical band gap, regardless of the type and concentration of the doping impurity. Also, the
infl uence of the deposition temperature and the activating impurity on the optical band gap of
synthesized sulphides has been studied. It was established that the fi lms of the CdS–ZnS system
are polycrystalline and they crystallize in the wurtzite structure.
Conclusion. It was found that the absorption edge of all the studied CdS–ZnS fi lms shifted to
the short-wave area with an increase of zinc sulphide content in them and the optical band gap
expands, respectively. Increase in the impurity concentration up to 10–3 at % and temperature
increase up to 500 °C led to the reduction of the optical band gap of the synthesized samples
due to the changes in their defect and band structure

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DOI: https//doi.org/10.1134/S1063782606100034