High-temperature degradation in plasma-enhanced chemical vapor deposition Al{sub 2}O{sub 3} surface passivation layers on crystalline silicon
- Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstraße 2, D-79110 Freiburg (Germany)
- Freiburg Materials Research Center FMF, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Straße 21 (Germany)
- Department of Microsystems Engineering IMTEK, Albert-Ludwigs-Universität Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg (Germany)
In this publication, the activation and degradation of the passivation quality of plasma-enhanced chemical vapor deposited aluminum oxide (Al{sub 2}O{sub 3}) layers with different thicknesses (10 nm, 20 nm, and 110 nm) on crystalline silicon (c-Si) during long and high temperature treatments are investigated. As indicated by Fourier Transform Infrared Spectroscopy, the concentration of tetrahedral and octahedral sites within the Al{sub 2}O{sub 3} layer changes during temperature treatments and correlates with the amount of negative fixed charges at the Si/Al{sub 2}O{sub 3} interface, which was detected by Corona Oxide Characterization of Semiconductors. Furthermore, during a temperature treatment at 820 °C for 30 min, the initial amorphous Al{sub 2}O{sub 3} layer crystallize into the γ-Al{sub 2}O{sub 3} structure and was enhanced by additional oxygen as was proven by x-ray diffraction measurements and underlined by Density Functional Theory simulations. The crystallization correlates with the increase of the optical density up to 20% while the final Al{sub 2}O{sub 3} layer thickness decreases at the same time up to 26%. All observations described above were detected to be Al{sub 2}O{sub 3} layer thickness dependent. These observations reveal novel aspects to explain the temperature induced passivation and degradation mechanisms of Al{sub 2}O{sub 3} layers at a molecular level like the origin of the negative fixe charges at the Si/SiO{sub x}/Al{sub 2}O{sub 3} interface or the phenomena of blistering. Moreover, the crystal phase of Al{sub 2}O{sub 3} does not deliver good surface passivation due to a high concentration of octahedral sites leading to a lower concentration of negative fixed charges at the interface.
- OSTI ID:
- 22314568
- Journal Information:
- Journal of Applied Physics, Vol. 116, Issue 5; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
ALUMINIUM OXIDES
BLISTERS
CHEMICAL VAPOR DEPOSITION
CRYSTALLIZATION
CRYSTALS
DENSITY FUNCTIONAL METHOD
FOURIER TRANSFORM SPECTROMETERS
INTERFACES
LAYERS
ORIGIN
PASSIVATION
PLASMA
SEMICONDUCTOR MATERIALS
SILICON
SILICON OXIDES
SIMULATION
SURFACES
THICKNESS
X-RAY DIFFRACTION