Band gap tuning with Bi and Ag deposition on Bi(Ag)/Sb2S3 bilayer thin film

Bilayer thin films of Bi/Sb2S3 and Ag/Sb2S3 were prepared by thermal evaporation method in high vacuum condition. X-ray diffraction study (XRD) revealed the amorphous nature of all the films as no sharp peak was found. SEM study indicated the smooth surface for the three films. The elemental presence was confirmed from EDX study. The optical transmission was studied by FTIR spectroscopy in the range 500-1200 nm. The transmission % is found to be decreased and absorption coefficient increased with the deposition of 10 nm Bi and Ag layer onto Sb2S3 film. The optical band gap calculated by Tauc’s relation shows anincrease in band gap from 1.54 eV (Sb2S3) to 1.60 eV (Bi/Sb2S3) and 1.64 eV(Ag/Sb2S3)with Bi and Ag deposition onto Sb2S3 layer. This increase in optical band gap is discussed in terms of defect states and degree of disorderness.Bilayer thin films of Bi/Sb2S3 and Ag/Sb2S3 were prepared by thermal evaporation method in high vacuum condition. X-ray diffraction study (XRD) revealed the amorphous nature of all the films as no sharp peak was found. SEM study indicated the smooth surface for the three films. The elemental presence was confirmed from EDX study. The optical transmission was studied by FTIR spectroscopy in the range 500-1200 nm. The transmission % is found to be decreased and absorption coefficient increased with the deposition of 10 nm Bi and Ag layer onto Sb2S3 film. The optical band gap calculated by Tauc’s relation shows anincrease in band gap from 1.54 eV (Sb2S3) to 1.60 eV (Bi/Sb2S3) and 1.64 eV(Ag/Sb2S3)with Bi and Ag deposition onto Sb2S3 layer. This increase in optical band gap is discussed in terms of defect states and degree of disorderness.