Regensburg 2025 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 6: Thin Film Application

DS 6.4: Vortrag

Mittwoch, 19. März 2025, 10:15–10:30, H3

VO₂ Smart Windows for Applications: A Study of Cu_xTi_1−xO₂ Buffer Layers in Multilayer Thin Film Systems — •Hao Lu^1,2, Martin Becker^1,2, Jan Luka Dornseifer^1,2, and Peter J. Klar^1,2 — ¹Institute of Experimental Physics I, Justus-Liebig-University, Giessen, Germany — ²Center of Materials Research (ZfM/LaMa), Justus Liebig University Giessen, Giessen, Germany

Alloying the TiO₂ with CuO₂ yielding Cu_xTi_1−xO₂ may provide a suitable buffer layer for optical smart windows based on VO₂. Preliminary work in the literature suggests that the phase transition temperature of the anatase to rutile structural phase transition of TiO₂ is lowered for by alloying Cu. However, that the band gap of Cu_xTi_1−xO₂ decreases with increasing x compared with the wide band gap of TiO₂. We successfully grew polycrystalline Cu_xTi_1−xO₂ alloys with x up to 31% on quartz substrates. We determined the crystal phase of the deposited thin films by XRD and Raman spectroscopy and established a 2D phase map versus substrate temperature during growth and Cu content x. It shows that increasing Cu content considerably lowers the growth temperature where rutile Cu_xTi_1−xO₂ thin films can be obtained. Furthermore, we find that the morphology of the Cu_xTi_1−xO₂ thin films changes with increasing x. Currently, we are assessing the trade-off between band gap, morphology, and growth temperature required for obtaining the most suitable rutile Cu_xTi_1−xO₂ buffer layer from the viewpoints of the best materials properties as well as a suitability for future commercialization in smart windows.

Keywords: Vanadium dioxide; Smart windows; Buffer layer