Influence of phase transformation on structure–property relationship in quaternary In₁₀Sb₁₀Ag₁₀Se₇₀ chalcogenide films

This work reports the effect of thermal annealing (353–413 K) on structure and physical properties of thermally evaporated In₁₀Ag₁₀Sb₁₀Se₇₀ chalcogenide films. The samples were characterized by X-ray diffraction, transmission electron microscopy, TEM, Raman spectroscopy, optical absorption and photoconductivity measurements. Thermal annealing favours amorphous to polycrystalline structure transition with the growth of Se, AgInSe₂ and AgSbSe₂ phases. A significant change in position/shape of Raman bands upon annealing has been observed. The indirect optical gap decreases from 1.44 to 0.68 eV while tailing parameter increases with annealing. Photosensitivity decreases from 29.3 to 14.2 with annealing temperature. The decay of photocurrents is well fitted to stretched exponential function; the value of decay time constant increases while local minimum value of dispersion parameter at 353 K has been observed. These results are explained on the basis of amorphous crystalline phase transformation in chalcogenides and are important for developing new materials for emerging technologies.