Influence of thickness on structural properties of annealed $\mathrm{In_2S_3}$ thin films deposited by thermal evaporation

$\mathrm{In_2S_3}$ thin films of various thicknesses were deposited onto glass substrates by thermal evaporation technique. Thicknesses of $\mathrm{In_2S_3}$ films were defined by controlling the deposition parameters and were $1200$ nm, $470$ nm and $50$ nm. All prepared thin films were annealed at $400^\circ$C for $60$ min. The structural properties and morphology have been studied by $\mathrm{X}$-ray diffraction, Raman spectroscopy and Atomic force microscopy. $\mathrm{X}$-ray diffraction results of $\mathrm{In_2S_3}$ thin films with thicknesses of $1200$ nm and $470$ nm demonstrated peaks revealed in tetragonal structure. Raman spectroscopy shows that the intensity of peaks is affected by the film thickness. The average roughness ($R_a$) and the root mean square roughness ($R_{\text{RMS}}$) increases with thickness. This is associated with the increase of grain size in the $\mathrm{In_2S_3}$ films.