Physical properties of Cu2MgSnS4 thin films prepared by chemical spray pyrolysis technique: The effect of thiourea concentration

Abstract

In this work, chemical spray pyrolysis is employed to prepare Cu2MgSnS4 thin films using different concentrations of thiourea (0.14, 0.16, 0.18, 0.20, 0.22, 0.24) M at a substrate temperature of 400 ℃ and thickness of (300±10) nm. The XRD results displayed that all thin films are polycrystalline with tetragonal structure and favorite orientation along the (112) plane. The crystallite size of films is estimated by Scherrer's equation and it was found that it increases with increasing thiourea concentration up to 0.20 M and then it decreases with further increase in thiourea concentration. The FESEM result exhibited the appearance of nanostructures with different particle sizes and shapes. The band gap was estimated using Tauc's relationship and it was found that the value of the band gap increases with increasing thiourea concentration from 1.68 eV at 0.14 M to 1.83 eV at 0.20 M and then it decreases to 1.60 eV at 0.24 M. Raman spectroscopy investigation confirms the purity of the sample formation phase. The main peak for all films is located at about 330 cm-1 . The broadening of this peak in solid solutions can be attributed to the disturbance effects related to the locations of the metal and sulfur atoms in the tetrahedral lattice due to chemical substitutions in the crystalline positions. Hall effect results showed that all films are P-type. The increase in carrier concentration and its motility with increasing thiourea concentrations leads to a decrease in the resistance of the films.