SYNTHESIS AND PROPERTIES OF THE CDS-ZNS FILMS DOPED BY COPPER IONS

Abstract

The main purpose of this work was to study the effect of the doping impurity of copper ions (10–7 – 10–3 at. %) on the crystal structure, optical and luminescent properties of CdS–ZnS fi lms prepared by spray pyrolysis method from thiourea complex compounds [М(N2H4CS)2Br2] (М = Cd,Zn) at a temperature of 400 °C. X-ray diffractometry was used to determination of the crystal structure and phase composition of the obtained fi lms. It is established that at the used conditions of the fi lms deposition in the system CdS–ZnS unbounded solid solutions of the wurtzite structure are formed. To determine the optical band gap, the absorption spectra of the fi lms in the region of the self-absorption edge were studied. It was found that the optical band gap of the samples varies from 2.46 to 3.84 eV with an increase in the content of zinc sulphide in them. It was found that the impurity of copper ions at used concentrations does not have a strong effect on the optical band gap. Photoluminescence spectra of CdxZn1–xS fi lms contain a wide complex band in the region of 400–800 nm. The position of the photoluminescence maximum shifts to the short-wavelength region with an increase in the content of zinc sulphide in the samples. The highest intensity of luminescence is characteristic for CdxZn1–xS fi lms with a high content of cadmium sulphide. It is established that at the concentration of copper ions at 10–7–10–5 at. % the high photoluminescence intensity of CdxZn1–xS fi lms is observed, the maximum value is it at the dopant concentration of 10–6 at. %.

Keywords

• aerosol pyrolysis method
• thiourea complex compounds
• fi lms
• sulphides of cadmiumzinc
• optical bandgap
• photoluminescence spectra.