Properties of the c-Si/Al{sub 2}O{sub 3} interface of ultrathin atomic layer deposited Al{sub 2}O{sub 3} layers capped by SiN{sub x} for c-Si surface passivation
- Fraunhofer Institute for Solar Energy Systems (ISE), Heidenhofstrasse 2, 79110 Freiburg (Germany)
This work presents a detailed study of c-Si/Al{sub 2}O{sub 3} interfaces of ultrathin Al{sub 2}O{sub 3} layers deposited with atomic layer deposition (ALD), and capped with SiN{sub x} layers deposited with plasma-enhanced chemical vapor deposition. A special focus was the characterization of the fixed charge density of these dielectric stacks and the interface defect density as a function of the Al{sub 2}O{sub 3} layer thickness for different ALD Al{sub 2}O{sub 3} deposition processes (plasma-assisted ALD and thermal ALD) and different thermal post-deposition treatments. Based on theoretical calculations with the extended Shockley–Read–Hall model for surface recombination, these interface properties were found to explain well the experimentally determined surface recombination. Thus, these interface properties provide fundamental insights into to the passivation mechanisms of these Al{sub 2}O{sub 3}/SiN{sub x} stacks, a stack system highly relevant, particularly for high efficiency silicon solar cells. Based on these findings, it was also possible to improve the surface passivation quality of stacks with thermal ALD Al{sub 2}O{sub 3} by oxidizing the c-Si surface prior to the Al{sub 2}O{sub 3} deposition.
- OSTI ID:
- 22395455
- Journal Information:
- Applied Physics Letters, Vol. 105, Issue 23; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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