EFFECT OF SUBSTRATE TEMPERATURE ON OPTICAL PROPERTIES OF Bi2S3CHALCOGENIDE THIN FILMS

摘要

Polycrystalline Bi2S3thin films were prepared by a spray pyrolysis technique on glass substrate. The influence of substrate temperature on the structural and optical properties has been studied. The crystal structure and orientation of the prepared films were investigated by x-ray diffraction and observed that bismuth sulfide corresponds to orthorhombic crystal structure. The surface morphology was studied using field emission scanning electron microscopy. We have studied the variation in crystallite size and grain size with substrate temperature and observed a linear increase in crystallite size with substrate temperature along with increase in the size of grains. The size increment of the particles with substrate temperature was explained in terms of Ostwald ripening. The absorption spectra have been taken in the wavelength range 500 nm to 800 nm. The direct band gap of thin films was calculated from absorption spectra, which reveals that band gap decreases as the substrate temperature increases