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PECVD Al 2 O 3 /a‐ S i: B as a dopant source and surface passivation
Author(s) -
Seiffe Johannes,
Gahoi Amit,
Hofmann Marc,
Rentsch Jochen,
Preu Ralf
Publication year - 2013
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201228850
Subject(s) - passivation , materials science , dopant , boron , silicon , annealing (glass) , plasma enhanced chemical vapor deposition , amorphous silicon , optoelectronics , doping , layer (electronics) , analytical chemistry (journal) , crystalline silicon , nanotechnology , composite material , chemistry , organic chemistry , chromatography
In this study, a two‐layer system consisting of a thin aluminum oxide (Al 2 O 3 ) and a heavily boron‐doped amorphous silicon (a‐Si:B) is described. The double layer can be applied as a boron‐dopant source in high‐temperature diffusion as well as for surface passivation afterwards. The influence of different Al 2 O 3 thicknesses and diffusion processes is investigated regarding the boron diffusion, surface passivation, and optical characteristics of this layer stack. Using a 5‐nm thick Al 2 O 3 film, a stable surface passivation as well as significant boron diffusion through the Al 2 O 3 is possible. The best surface passivation is achieved for the annealing process with the highest thermal budget (950 °C for 60 min). Investigations by spectral ellipsometry prove the growth of silicon dioxide during the high‐temperature diffusion process and indicate that the remaining boron‐rich silicon layer is highly absorbing even for near‐bandgap, near‐infrared light. To improve future solar cells using this layer as the rear‐side coating, the thickness of this layer has to be reduced.