Investigation of the optical and structural properties of thermally evaporated cadmium sulphide thin films on polyethylene terephthalate substrate

• Published in: Materials science in semiconductor processing 2011-06, Vol.14 (2), p.146-150
• Main Authors: Faraj, M.G., Ibrahim, K., Eisa, M.H.
• Format: Article
• Language: English
• Subjects: Cadmium sulfides; Cadmium sulphide; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Film thickness; Fullerenes and related materials; Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Physics; Polyethylene terephthalate; Polyethylene terephthalates; Roughness; Semiconductors; Thermal evaporation; Thin films; Visible and ultraviolet spectra
• ISSN: 1369-8001; 1873-4081
• DOI: 10.1016/j.mssp.2010.12.016

Cadmium sulphide (CdS) thin films of different thicknesses ranging from 100 to 400 nm were prepared on polyethylene terephthalate (PET) substrates at room temperature by thermal evaporation technique in vacuum of about 3×10 −5 Torr. The structural characterisation was carried out by X-ray diffraction (XRD). These studies confirm the proper phase formation of the cadmium sulphide structure. The root mean square (RMS) roughness of the films was measured using atomic-force microscopy. The root mean square roughness of the films increases as the film thickness increases. The energy gap of CdS on PET substrates was determined through the optical transmission method using an ultraviolet–visible spectrophotometer. The optical band gap values of CdS thin films slightly increase as the film thickness increases. The optical band gap energy was found to be in the range of 2.41–2.56 eV.