Improvement of optoelectronic and spintronic properties of nanocrystalline Zn1-xGdxS films deposited by electron beam technique

Abstract This paper reports the enhancement of the optoelectronic and spintronic properties of nanocrystalline Gd-doped ZnS thin films synthesized by electron beam evaporation method. The structure and microstructural revealed the cubic structure film, and its average crystallite size reduced from 28.92 nm (x = 0) to 22.26 nm (x = 0.1), that confirmed the nanocrystalline nature of the film. Optical measurements exhibit that the Gd doping in ZnS caused the optical band gap to decrease due to the increase of defects. In addition, the refractive index n evaluated from the optical transmittance spectra through Swanepoel method is found to increase with Gd doping level owing to the increase in the polarizability. The dispersive oscillator parameters such as the single oscillator energy Eo, the dispersion energy Ed, the static refractive index n0 were calculated by Wemple and DiDomenico (WDD) model. The Non-linear optical parameters; third-order non-linear optical susceptibility χ(3) and non-linear refractive index n2 are evaluated from dispersive oscillator parameters. The results show that the tunability of the optical band gap and dispersive oscillator parameters of Gd-doped ZnS films reflects the enhancement of the non-linear optical parameters, making it suitable for optoelectronic device applications. Finally, the magnetic measurements results show that the Gd-doped ZnS film has intrinsic room temperature ferromagnetic behavior. These results indicate that Gd-doped ZnS film is effective for designing spintronic devices.