OPTICAL AND STRUCTURAL PROPERTIES OF Zn(1-x)FexS NANOPARTICLES SYNTHESIZED BY CHEMICAL BATH DEPOSITION METHOD

Nanoparticles of Zn1-xFexS with x = 0.0, 0.05, 0.1, 0.15, 0.2 and 0.3 were synthesized using the chemical bath deposition method, using tri-sodium citrate as a complexion agent. These nanoparticles were characterized using XRD, SEM, optical absorbance and photoluminescence. SEM micrographs of the films revealed the combination of Zn1-xFexS nanoparticles with an average particle size D similar to 60.3 to 19.3 nm +/- 0.01 nm for x = 0.0 to 0.3. X-ray diffraction patterns confirmed the nanocrystalline cubic ZnS phase formation. UV-visible spectrometer measurement showed high absorbance for Fe concentration x >= 0.15 in the wavelength range 325-800 nm. However, for x <= 0.1, the absorbance of the films decreased with further increase of Fe concentration. From the absorbance data, the direct bandgap values have been calculated to be in the range E-g = 3.5 to 2.23 eV for x = 0.0 to 0.3. The bandgap decreased with the increase of Fe concentration in the films. The photoluminescence spectra of the films showed two emission peaks, the first in the low wavelengths due to band-to-band transition, and the second in the high wavelengths due to the transitions probabilities and to the concentration of Fe ions. Due to the quenching effect, the intensity of PL spectra decreased on further increase of Fe doping.