Optical, magnetic, and photoelectrochemical properties of electrochemically deposited Eu3+-doped ZnSe thin films

Abstract

The various mole percent (1–5%) of Eu3+-doped ZnSe thin films were fabricated on the indium-doped tin oxide (ITO) conducting glass substrate by single-step electrochemical deposition (ECD) process in an aqueous medium at 50 °C. The structural, optical, magnetic, and electrochemical properties were characterized as a function of the Eu3+ ion concentration. The X-ray diffraction (XRD) analyses evidenced that the films were hexagonal wurtzite structure along with the (101) preferential orientation. High-resolution scanning electron microscopy (HRSEM) results revealed that the thin films show a spherical like structure for 1–3% of Eu3+-doped ZnSe films. Further, increasing of Eu3+ concentration (4 and 5%), the surface morphology of thin films was observed as agglomerated grain-like structure. The band gap energy of Eu3+-doped ZnSe thin films (2.35 to 2.49 eV) determined by UV-Vis spectra showed a blue shift of absorption edge compared to the pure ZnSe thin film (2.33 eV). The increased band gap by doping of Eu3+ is due to the quantum size effect. The PL emission intensity enhanced by increasing Eu3+ concentration which revealed the enhanced radiative recombination in the luminescence process. The magnetic study revealed that Eu3+-doped ZnSe thin films were ferromagnetic in nature. Electrochemical impedance analysis indicated that 4% of Eu3+-doped ZnSe thin films showed a lower charge transfer resistance (352 Ω) and excellent properties compared to the other samples. Further, the photoelectrochemical measurements carried out for the optimized 4% Eu3+-doped ZnSe thin film revealed the faster migration of photoinduced charge carriers. The present investigation demonstrates that the electrochemically deposited Eu3+-doped ZnSe thin film is a promising candidate for electrochemical device applications.