Comparative study of structural, optical and electrical properties of electrochemically deposited Eu, Sm and Gd doped ZnSe thin films

摘要

Abstract A facile approach involving electrochemical deposition method was utilized to coat ITO substrate with zinc selenide thin films at different rare earth metal (Eu_(3+), Sm_(3+)and Gd_(3+)) ions. The characteristics of deposited films were studied in relation with the doped metal ions. The structure of the coating was confirmed to be hexagonal wurtzite in (101) plane by X-ray analysis. The new antistructural modeling shows that the doping of ZnSe lattice by rare earth cations increases the concentration of the surface active centers such as $${text{Gd}}_{{{text{Zn}}}}^{cdot },,{text{Eu}}_{{{text{Zn}}}}^{cdot },,{text{Sm}}_{{{text{Zn}}}}^{cdot },,{text{and}},{text{V}^{primeprime}_{{text{Zn}}}}$$ Gd Zn · , Eu Zn · , Sm Zn · , and V Zn ″ , which are located in the cationic sublattice. XRD data revealed that the average crystallite size of ZnSe and ZnSe:Eu, ZnSe:Sm, and ZnSe:Gd was 63, 54, 47, and 49 nm, respectively. The morphological results by scanning electron microscopy indicate that the spherical-like structure with agglomeration of grains and a slight increase in the particle size. Energy dispersive X-ray, UV–Visible and photoluminescence spectroscopy were used to study the composition and optical properties of the films. A blue-shift was observed in ZnSe thin films. The bandgap energy of undoped ZnSe and ZnSe:Eu, ZnSe:Sm, and ZnSe:Gd were found to be 2.28, 2.44, 2.68 and 2.75 eV, respectively. Among the different coated films, the Gd_(3+)ion doped ZnSe thin film exhibited a lesser charge transfer resistance of 25.5 Ω as analyzed from the electrochemical impedance measurement. The photoelectrochemical studies reveal that the rate of photoinduced charge carriers was higher in Gd_(3+)ion doped thin film. The present studies suggested that the Gd_(3+)ion doped ZnSe thin film can be a promising material for electrochemical device applications.