Annealing study and thermal investigation on bismuth sulfide thin films prepared by chemical bath deposition in basic medium

Bismuth sulfide thin films were prepared by chemical bath deposition using thiourea as sulfide ion source in basic medium. First, the effects of both the deposition parameters on film growth as well as the annealing effect under argon and sulfur atmosphere on as-deposited thin films were studied. The parameters were found to be influential using the Doehlert matrix experimental design methodology. Ranges for a maximum surface mass of films (3 mg cm−2) were determined. A well-crystallized major phase of bismuth sulfide with stoichiometric composition was achieved at 190 °C for 3 h. The prepared thin films were characterized using grazing incidence X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray analysis. Second, the bandgap energy value was found to be 1.5 eV. Finally, the thermal properties have been studied for the first time by means of the electropyroelectric (EPE) technique. Indeed, the thermal conductivity varied in the range of 1.20–0.60 W m−1 K−1, while the thermal diffusivity values increased in terms of the annealing effect ranging from 1.8 to 3.5 10−7 m2 s−1.