Tuning filtering properties of SnS films deposited on Glass/ITO substrate using glancing angle deposition technique

In the present work, for the first time, a multilayer filter comprised of Tin sulfide (SnS) and Indium tin oxide (ITO) coated glass has been fabricated using physical vapor deposition (PVD) method. The ITO coated glass slide (as a commercial substrate) is situated at the bottom portion of the filter on which a SnS film is deposited that acts as a window layer. The consecutive use of these films leads to the interference phenomenon. Furthermore, the deposition of SnS film, as the window layer on the Glass/ITO substrate, has been engineered using glancing angle deposition (GLAD) technique that has remarkably resulted in diffraction phenomenon. As a result, to find the optimum deposition angle, SnS films have been prepared at incident flux angles of 0°, 45°, and 65° using GLAD technique. Then the structural and morphological properties of the samples were studied by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and Atomic Force Microscopy (AFM) techniques. More importantly, the optical properties including transmittance spectrum and absorption coefficient of the samples were investigated by UV-NIR spectrophotometer in the wavelength range of 500-2500 nm. The obtained results have shown improvement in the filtering properties of as-prepared filter upon increment of the deposition angle. The filtering properties are attributed to the interference and diffraction phenomena because of the multilayer structure having different refractive indices and an oblique layer applied by GLAD technique, respectively. Moreover, the filter produced at normal vapor incidence only transmits the infrared spectrum, while a shift towards lower wavelengths is observed upon applying the deposition angle of 65°. This sample is introduced as an appropriate filter in the visible spectrum because of being transparent only in certain wavelength range (800-1400 nm).