Evidence of Room Temperature Ferromagnetism in Zn1−xSnxS Thin Films

Abstract

Tin (Sn)-doped zinc sulfide (Zn1−xSnxS) thin films at different tin (Sn) concentrations (= 0.00, 0.02, 0.05, and 0.08) were coated onto Corning 7059 glass substrates using the electron beam evaporation technique. The films were subjected to different characterization techniques to study the physical properties of the thin films. The structural properties of the films were studied using a powder X-ray diffractometer (XRD), and it was found that the films were cubic in structure without any impurity phases. The crystallite size increased with an increase of Sn concentration, and the mean crystallite size was 21 nm. The chemical composition and surface morphology of the films were studied using scanning electron microscopy (FE-SEM) with energy-dispersive analysis of X-rays (EDAX). Optical properties such as transmittance and absorbance were recorded using a diffuse reflectance spectroscope (UV–vis–NIR). All the films exhibited high optical transmittance of 85% in the visible region of the solar spectrum. The band gap of the films was calculated using Tauc’s relation, and it was found that it increased from 3.53 to 3.57 eV with an increase in the Sn doping concentration from x = 0.02 to x = 0.08. The room temperature photoluminescence studies of the films were recorded using a fluorescence spectrophotometer, and it was found that the films exhibited a prominent emission peak at 420 nm. The magnetic properties of the films and glass substrates at room temperature were studied using a vibrating sample magnetometer. From this, it was found that the films were weakly ferromagnetic at room temperature and the strength of magnetization increased with an increase of doping concentration from x = 0.02 to x = 0.05 and decreased at higher doping concentrations (x = 0.08). The films showed high magnetization at x = 0.05. The films at x = 0.05 exhibited the magnetization (Ms), retentivity (Mr), and coercive fields (Hc) 18 × 10− 6 emu/cm3, 1.6 × 10− 6 emu/cm3, and 91.80 Oe, respectively.