Structural, morphological, optical, and nonlinear optical properties of fluorine-doped zinc oxide thin films deposited on glass substrates by the chemical spray technique

• Published in: Physica status solidi. A, Applications and materials science Applications and materials science, 2006-06, Vol.203 (8), p.1971-1981
• Main Authors: Castañeda, L., Morales-Saavedra, O. G., Acosta, D. R., Maldonado, A., de la L. Olvera, M.
• Format: Article
• Language: English
• Subjects: 42.65.Ky; 68.55.Jk; 78.40.Fy; 78.55.Et; 81.15.Rs; 81.40.Tv; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Other semiconductors; Physics
• ISSN: 1862-6300; 0031-8965; 1862-6319
• DOI: 10.1002/pssa.200521386

Fluorine‐doped zinc oxide thin films (ZnO:F) were deposited on sodocalcic glass substrates from an aged solution using a chemical spray technique. The effect of substrate temperature (T S) on the morphological, optical, and nonlinear optical (NLO) properties of the ZnO:F thin films was studied. These films were analysed using X‐ray diffraction, scanning electron microscopy, profilometry, optical transmittance, optical fluorescence, and second (SHG) and third harmonic generation (THG) techniques. A polycrystalline structure with a preferential growth along the ZnO(002) plane was found in all cases, with a corresponding average crystal size of less than 32 nm for the films. The morphology of the surfaces and some optical properties were found to be dependent on T S. The films deposited at low T S (400 °C) showed a uniform surface covered with needle‐like grains as well as SHG and THG response. In contrast, for the films deposited at 525 °C, a porous surface with irregular‐shaped grains was obtained and a substantial reduction of the SHG and THG response was detected. NLO χ (2)eff coefficients one order of magnitude larger than the χ (2)11 component of an α‐quartz reference crystal were measured for all ZnO:F thin films. The χ (3) values of the samples, under resonant conditions, were in the interesting range of 10–12 esu. Finally, a typical optical transmittance higher than 85% and a band gap (E g) of 3.4 eV were evaluated for films deposited under optimal conditions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)