Surface and optical characterization of yttrium hydride films deposited on regular glass to be used as switchable mirrors

• Published in: Surface and interface analysis Vol. 34; no. 1; pp. 311 - 315
• Main Authors: Velásquez, P., Castañer, R., de la Casa-Lillo, M. A., Sánchez-López, M. M., Mallavia, R., Moreno, I., Gutiérrez, A., Mateos, F.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.08.2002; Wiley
• Subjects: Chemical composition analysis, chemical depth and dopant profiling; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Materials testing; metal hydrides; Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity); 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; palladium; Physics; switchable mirrors; thin films; yttrium; Scanning electron microscopy; Inorganic compounds; Transition element compounds; Optical windows; Palladium; X-ray spectra; Surface analysis; Dispersive spectrometry; Transmittance; Thin films; Transition elements; Yttrium hydrides; Ultraviolet visible spectrum; Depth profiles; Vacuum deposition; X-ray photoelectron spectra; Semiconductor metal transition
• DOI: 10.1002/sia.1307
• ISSN: 0142-2421

Yttrium and palladium thin films deposited on glass have been characterized by means of XPS depth profiling, SEM, energy‐dispersive x‐ray spectroscopy and ultraviolet–visible spectroscopy. These films allow optical windows of variable transparency to be obtained based on the formation of yttrium hydride by hydrogenation, with the palladium film working as a barrier against yttrium oxidation but being permeable to hydrogen. The transformation of yttrium into its hydride is concomitant with a metal–semiconducting transition that changes the physical properties of the material, especially its optical behaviour: the transmittance in the visible range goes from 0% for the metallic state to 30–70% for the hydrogenated state. In this work, the preparation conditions of optical windows using low‐cost regular glass as substrate have been optimized, both regarding the deposition and the hydrogenation. Uniform films free of impurities, such as oxygen and carbon, have been obtained under ultrahigh vacuum conditions of ∼10−7 Pa. Deposition has been performed by electron bombardment of the material, using palladium and yttrium of high purity. Copyright © 2002 John Wiley & Sons, Ltd.