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Title: Excellent c-Si surface passivation by low-temperature atomic layer deposited titanium oxide

In this work, we demonstrate that thermal atomic layer deposited (ALD) titanium oxide (TiO{sub x}) films are able to provide a—up to now unprecedented—level of surface passivation on undiffused low-resistivity crystalline silicon (c-Si). The surface passivation provided by the ALD TiO{sub x} films is activated by a post-deposition anneal and subsequent light soaking treatment. Ultralow effective surface recombination velocities down to 2.8 cm/s and 8.3 cm/s, respectively, are achieved on n-type and p-type float-zone c-Si wafers. Detailed analysis confirms that the TiO{sub x} films are nearly stoichiometric, have no significant level of contaminants, and are of amorphous nature. The passivation is found to be stable after storage in the dark for eight months. These results demonstrate that TiO{sub x} films are also capable of providing excellent passivation of undiffused c-Si surfaces on a comparable level to thermal silicon oxide, silicon nitride, and aluminum oxide. In addition, it is well known that TiO{sub x} has an optimal refractive index of 2.4 in the visible range for glass encapsulated solar cells, as well as a low extinction coefficient. Thus, the results presented in this work could facilitate the re-emergence of TiO{sub x} in the field of high-efficiency silicon wafer solar cells.
Authors:
 [1] ;  [2] ;  [3] ;  [1] ; ;  [1] ;  [2] ;  [4]
  1. Solar Energy Research Institute of Singapore, National University of Singapore, 7 Engineering Drive 1, Singapore 117574 (Singapore)
  2. (Singapore)
  3. (IMRE), 3 Research Link, Singapore 117602 (Singapore)
  4. A*STAR Institute of Materials Research and Engineering (IMRE), 3 Research Link, Singapore 117602 (Singapore)
Publication Date:
OSTI Identifier:
22303879
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 25; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ALUMINIUM OXIDES; DEPOSITION; FILMS; GLASS; LAYERS; PASSIVATION; RECOMBINATION; REFRACTIVE INDEX; SILICON; SILICON NITRIDES; SILICON OXIDES; SOLAR CELLS; STOICHIOMETRY; SURFACES; TITANIUM OXIDES; VISIBLE RADIATION