TiOx/Ag/TiOx multilayer for application as a transparent conductive electrode and heat mirror

• Published in: Journal of materials science. Materials in electronics 2013-07, Vol.24 (7), p.2461-2468
• Main Authors: Wu, Chu-Chun, Chen, Pang Shiu, Peng, Cheng-Hsiung, Wang, Ching-Chiun
• Format: Article
• Language: English
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; Materials; Materials Science; Methods of deposition of films and coatings; film growth and epitaxy; Molecular, atomic, ion, and chemical beam epitaxy; Optical and Electronic 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; Physics; Solid surfaces and solid-solid interfaces; Surface structure and topography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-013-1118-1

Amorphous TiO x films and Ag layer were deposited by electron-beam evaporation on soda-lime glass at room temperature. The details regarding the structure, surface morphology, and optical properties of the as-prepared TiO x films were examined by X-ray diffraction, scanning electron microscopy, and ultra-violet (UV) -visible-near-infrared (NIR) spectrometry. The TiO x films exhibit amorphous phase with an optical band gap of 3.35 eV. The polygrains oriented along the (111) and (200) directions in the Ag films were adopted to supply carriers into the TiO x film and lower the sheet resistance of the stacked layer. The multilayer exhibited a sufficiently large Ag thickness (>15 nm), low resistance, high UV transmittance, visible transmittance, and high NIR reflection. Dependence of Ag thickness, TiO x bottom-layer, and TiO x overlayer on the optical and electrical properties of TiO x /Ag/TiO x were explored. A figure of merit (FOM) was used to find an optimal structure for a multilayer with superior conductivity and visible transparency. An FOM of 9.8 × 10 −2 (Ω −1 ) at the visible wavelength of 550 nm for a TiO x /Ag/TiO x stacked layer with an 18-nm-thick Ag and a 20-nm-thick TiO x was achieved. The TiO x /Ag/TiO x sample annealed at 500 °C 10 min also shows a good thermal stability.