X-ray diffraction and X-ray photoelectron spectroscopy characterization of sulfurized tin thin films deposited by thermal evaporation

Highlights: • Techniques for obtaining SnS films by sulfurization using S powder are described. • The films showed a band gap of 1.2 eV and an absorption coefficient of > 10⁴ cm⁻¹. • Crystal growth along the SnS [040] direction was revealed by XRD. - Abstract: In this paper, we report the structural properties of tin sulfide (SnS) thin films deposited by a technique involving thermal evaporation and sulfurization. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to determine the crystallinity and elemental composition of the sulfurized tin thin films. With increasing sulfurization temperature, Sn and its native oxide reacted with S, yielding SnS. XRD showed evidence of crystal growth along the SnS [040] direction in films sulfurized at 260 and 300 °C. The growth of SnS crystals was completed at 300 °C, and stoichiometry was the highest. Depth profiles of the composition measured by XPS showed a flat sulfur concentration towards the interior of the film sulfurized at 300 °C. The hole concentration was 1.6 × 10¹⁵ cm⁻³. The films showed a band gap of 1.2 eV and an absorption coefficient of > 10⁴ cm⁻¹.