title: Breakdown and Protection of ALD Moisture Barrier Thin Films.
abstract: The water vapor barrier properties of low-temperature atomic layer deposited (ALD) AlOx thin-films are observed to be unstable if exposed directly to high or even ambient relative humidities. Upon exposure to humid atmospheres, their apparent barrier breaks down and their water vapor transmission rates (WVTR), measured by electrical calcium tests, deteriorate by several orders of magnitude. These changes are accompanied by surface roughening beyond the original thickness, observed by atomic force microscopy. X-ray reflectivity investigations show a strong decrease in density caused by only 5 min storage in a 38 °C, 90% relative humidity climate. We show that barrier stabilities required for device applications can be achieved by protection layers which prevent the direct contact of water condensing on the surface, i.e., the sensitive ALD barrier. Nine different protection layers of either ALD materials or polymers are tested on the barriers. Although ALD materials prove to be ineffective, applied polymers seem to provide good protection independent of thickness, surface free energy, and deposition technique. A glued-on PET foil stands out as a low-cost, easily processed, and especially stable solution. This way, 20 nm single layer ALD barriers for organic electronics are measured. They yield reliable WVTRs down to 2×10(-5) g(H2O) m(-2) day(-1) at 38 °C and 90% relative humidity, highlighting the great potential of ALD encapsulation.
authors.affiliation: Institut für Angewandte Photophysik, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Frederik
authors.initials: F
authors.lastname: Nehm
authors.affiliation: Institut für Angewandte Photophysik, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Hannes
authors.initials: H
authors.lastname: Klumbies
authors.affiliation: NaMLab gGmbH , Nöthnitzer Straße 64, 01187 Dresden, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Richter
authors.affiliation: NaMLab gGmbH , Nöthnitzer Straße 64, 01187 Dresden, Germany.
authors.forename: Aarti
authors.initials: A
authors.lastname: Singh
authors.affiliation: NaMLab gGmbH , Nöthnitzer Straße 64, 01187 Dresden, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Schroeder
authors.affiliation: NaMLab gGmbH , Nöthnitzer Straße 64, 01187 Dresden, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Mikolajick
authors.affiliation: Institut für Angewandte Photophysik, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Mönch
authors.affiliation: Institut für Halbleiter und Mikrosystemtechnik, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Hoßbach
authors.affiliation: Institut für Halbleiter und Mikrosystemtechnik, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Albert
authors.affiliation: Institut für Halbleiter und Mikrosystemtechnik, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Johann W
authors.initials: JW
authors.lastname: Bartha
authors.affiliation: Institut für Angewandte Photophysik, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Leo
authors.affiliation: Institut für Angewandte Photophysik, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Müller-Meskamp
keywords: WVTR; atomic layer deposition; barrier; corrosion; encapsulation; water vapor