Environmentally induced chemical and morphological heterogeneity of zinc oxide thin films

Journal Article · Mon Aug 29 00:00:00 EDT 2016 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4962203· OSTI ID:22590464

Jiang, Hua ^[1]; Chou, Kang Wei ^[2]; Petrash, Stanislas ^[3]; Williams, Garth; Thieme, Juergen; Li, Li; Nykypanchuk, Dmytro ^[4]; Muto, Atsushi ^[5]

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1. Department of Materials Science and Engineering, Stony Brook University, Stony Brook, New York 11790 (United States)
2. Henkel Ibérica S. A. Edificio Eureka, 08193, Campus UAB, Barcelona (Spain)
3. Henkel Corporation, 10 Finderne Avenue, Bridgewater, New Jersey 08807 (United States)
4. Center for Functional Nanomaterials, Brookhaven National Laboratory, 735 Brookhaven Avenue, Upton, New York 11973-5000 (United States)
5. Hitachi High Technologies America, 22610 Gateway Center Drive, Clarksburg, Maryland 20871 (United States)

Zinc oxide (ZnO) thin films have been reported to suffer from degradation in electrical properties, when exposed to elevated heat and humidity, often leading to failures of electronic devices containing ZnO films. This degradation appears to be linked to water and oxygen penetration into the ZnO film. However, a direct observation in the ZnO film morphological evolution detailing structural and chemical changes has been lacking. Here, we systematically investigated the chemical and morphological heterogeneities of ZnO thin films caused by elevated heat and humidity, simulating an environmental aging. X-ray fluorescence microscopy, X-ray absorption spectroscopy, grazing incidence small angle and wide angle X-ray scattering, scanning electron microscopy (SEM), ultra-high-resolution SEM, and optical microscopy were carried out to examine ZnO and Al-doped ZnO thin films on two different substrates—silicon wafers and flexible polyethylene terephthalate (PET) films. In the un-doped ZnO thin film, the simulated environmental aging is resulting in pin-holes. In the Al-doped ZnO thin films, significant morphological changes occurred after the treatment, with an appearance of platelet-shaped structures that are 100–200 nm wide by 1 μm long. Synchrotron x-ray characterization further confirmed the heterogeneity in the aged Al-doped ZnO, showing the formation of anisotropic structures and disordering. X-ray diffraction and X-ray absorption spectroscopy indicated the formation of a zinc hydroxide in the aged Al-doped films. Utilizing advanced characterization methods, our studies provided information with an unprecedented level of details and revealed the chemical and morphologically heterogeneous nature of the degradation in ZnO thin films.

• OSTI ID: 22590464
• Journal Information: Applied Physics Letters, Vol. 109, Issue 9; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION
ABSORPTION SPECTROSCOPY
AGING
DOPED MATERIALS
ELECTRICAL PROPERTIES
ELECTRON SCANNING
ELECTRONIC EQUIPMENT
FLUORESCENCE
MORPHOLOGICAL CHANGES
OPTICAL MICROSCOPY
POLYETHYLENES
POSITRON COMPUTED TOMOGRAPHY
SCANNING ELECTRON MICROSCOPY
SYNCHROTRONS
THIN FILMS
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY
ZINC HYDROXIDES
ZINC OXIDES