Impact of the annealing time on physical properties of sprayed In2S3 thin films

Indium sulfide thin films were deposited on preheated soda-lime glass substrates using spray technique over experiment optimum conditions (Ts = 340 °C, S/In = 2). The effect of annealing time on structural, morphological, optical and electrical properties of the films was investigated. X-ray diffraction spectra show that In2S3 films are polycrystalline with a cubic phase and preferentially oriented towards (400) for different annealing times. It is found that the film grain size increases from 39 to 49 nm when increasing the annealing time from 1 to 5 h. Both field emission scanning electron microscopy and atomic force microscopy images show that the surface morphology is strongly dependent upon the annealing time. Electron dispersive X-ray spectroscopy reveals that the film composition is not affected by the annealing. Raman spectroscopy analysis shows the predominance of active modes of β-ln2S3 films with annealing time. Optical band gap is found to vary in the range 2.38–2.63 eV for direct transitions. At room temperature, Hall effect measurements show that the mobility (µ) and the carrier concentration (nv) vary in the ranges 1.65–29.3 cm2 V−1 s−1 and 1.16 × 1017–2.82 × 1017 cm−3, respectively. Also, the electrical resistivity of the films is reduced from 14.47 to 1.65 Ω cm with increasing annealing time. The results are in good agreement with available literature and showed its future use in many optoelectronics devices.