Study of Structural and Optical Properties of Undoped and Cd Doped SnO_2 Thin Films Prepared by Sol-Gel Dip Coating Technique

摘要

In this study, we report the study of the surface morphology, the structural and optical proprieties of transparent cadmium doped tin dioxide (Cd:SnO_2) thin films deposited on glass and Si(100) substrates by Sol Gel Dip Coating (SGDC) technique. The analysis was carried out using Grazing Incidence X-Ray Diffraction (GIXRD), Atomic Force Microscopy (AFM), UV-Vis spectrophotometry and Spectroscopic Ellipsometry (SE). The X-ray diffraction reveals that all films deposited on Si(100) substrate have tetragonal crystalline structure with preferential orientation along (310) plane, but an amorphous structure is obtained for all the films prepared on glass substrate. The surface roughness, observed by means of AFM varies from 19 to 4 nm. The optical measurements show that the deposited Cd;SnO_2 films have a high transparency (~86%) in the visible spectrum and a band gap energy decreasing from 3.60 eV to 3.31 eV with increasing Cd concentration. The obtained values of the refractive index of the films are ranging between 1.559 and 1.613.