Crystal structure and optical absorption investigations on β-In2S3 thin films

• Published in: Thin solid films 2006-12, Vol.515 (4), p.1796-1801
• Main Authors: El-Nahass, M.M., Khalifa, B.A., Soliman, H.S., Seyam, M.A.M.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Crystal structure; Evaporation; Exact sciences and technology; Indium selinide; Optical absorption; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics; Single-crystal and powder diffraction; Structure and morphology; thickness; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; X-ray diffraction; X-ray diffraction and scattering
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2006.06.036

The crystal structure of annealed β-In2S3 thin films with different thickness was investigated by X-ray diffraction technique. Lattice parameters, crystallite size and microstrain were calculated. It was found that the lattice parameters are independent on film thickness, while annealing temperatures increase them. Crystallite sizes were increased with the increase of the film thickness and improved by annealing temperatures. In all cases, the microstrains were decreased gradually with the increase in both film thickness and annealing temperatures. Optical properties of β-In2S3 thin films were performed in the spectral range from 400 to 2500 nm to determine the optical constants (n and k), the high frequency dielectric constant, ε∞, the lattice dielectric constant, εL, and the energy gap. The optical constants were found to be independent on film thickness in the range from 200 to 630 nm. The high frequency dielectric and lattice dielectric constants of the as-deposited film increased by annealing temperatures. The energy gap for the as-deposited In2S3 was found to be 2.60 eV and increased to 2.70 and 2.75 eV by annealing at 423 and 473 K for 1 h, respectively.