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Comparison of TiO 2 and other dielectric coatings for buried‐contact solar cells: a review
Author(s) -
Richards B. S.
Publication year - 2004
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.529
Subject(s) - passivation , materials science , dielectric , diffusion barrier , silicon nitride , chemical vapor deposition , solar cell , crystalline silicon , silicon dioxide , silicon , silicon oxynitride , chemical engineering , nanotechnology , optoelectronics , layer (electronics) , composite material , engineering
This paper compares the optical, electronic, physical and chemical properties of dielectric thin films that are commonly used to enhance the performance of bulk silicon photovoltaic devices. The standard buried‐contact (BC) solar cell presents a particularly challenging set of criteria, requiring the dielectric film to act as: (i) an anti‐reflection (AR) coating; (ii) a film compatible with surface passivation; (iii) a mask for an electroless metal plating step; (iv) a diffusion barrier for achieving a selective emitter; (v) a film with excellent chemical resistance; (vi) a stable layer during high‐temperature processing. The dielectric coatings reviewed here include thermally grown silicon dioxide (SiO 2 ), silicon nitride deposited by plasma‐enhanced chemical vapour deposition (a‐ SiN x :H) and low‐pressure chemical vapour deposition (Si 3 N 4 ), silicon oxynitride (SiON), cerium dioxide (CeO 2 ), zinc sulphide (ZnS), and titanium dioxide (TiO 2 ). While TiO 2 dielectric coatings exhibit the best optical performance and a simple post‐deposition surface passivation sequence has been developed, they require an additional sacrificial diffusion barrier to survive the heavy groove diffusion step. A‐ SiN x :H affords passivation through its high fixed positive charge density and large hydrogen concentration; however, it is difficult to retain these electronic benefits during lengthy high‐temperature processing. Therefore, for the BC solar cell, Si 3 N 4 films would appear to be the best choice of dielectric films common in industrial use. Copyright © 2004 John Wiley & Sons, Ltd.