TY - GEN
T1 - Crystalline silicon solar cells with doped epitaxial silicon films obtained at low-temperature by PECVD
AU - Damon-Lacoste, J.
AU - Labrune, M.
AU - Granata, S.
AU - Daineka, D.
AU - Cabarrocas, P. Rocai
PY - 2010/12/20
Y1 - 2010/12/20
N2 - In spite of dramatic improvements in thin film technologies, crystalline silicon (c-Si) solar cells are still leading the photovoltaic market thanks to continuous progress. In this field, one innovative way is the development of thin silicon epitaxial films (epi-Si) on (100) c-Si wafers to fabricate the emitter and/or back surface field of solar cells. Among the possible techniques, we used radio-frequency plasma enhanced chemical vapor deposition (rf-PECVD) for it is a low thermal budget, scalable, wide-spread process in photovoltaics and it is well-suited to make solar cells on thin c-Si wafers (< 150 μm) without too much stress induced. In this paper, we report the obtaining of n-type epi-Si layers and p-type epi-Si layers by adding a proper amount of phosphine (PH3), diborane (B2H6) or trimethylboron (TMB) to the gas phase as well as appropriately adjusting the deposition temperature, pressure and silane gas flow. For n-type epi-Si layers, we managed to obtain degenerate levels of doping while maintaining the epitaxial growth quality of Si films whereas for p-type we obtained highly doped epi-Si lalers with hole concentration spreading from 2.1018 cm-3 to 6.1019 cm-3 (at 300 K). Another noticeable result is that the deposition temperature dependence of the boron-doped epi-Si films changes according to the doping gas used (TMB or B2H6). This behavior has to be opposed to intrinsic epi-Si for which the higher the temperature the better the epitaxy. We also pay a particular attention to reproducibility of doping levels for n-type and p-type epi-Si layers. Finally, we fabricated c-Si solar cells with p-type epi-Si emitter (entirely epitaxial) and a-Si:H back contact (intrinsic and n-type). In this work we compare our previous results based on laser-cutting and screen-printing for which we achieved an efficiency of 14.2 % [1] with a new fully in-house process in which only SF6 etching is used to define the solar cells and evaporated silver contacts are used for the front grid leading to a solar cell efficiency of 13.4 %.
AB - In spite of dramatic improvements in thin film technologies, crystalline silicon (c-Si) solar cells are still leading the photovoltaic market thanks to continuous progress. In this field, one innovative way is the development of thin silicon epitaxial films (epi-Si) on (100) c-Si wafers to fabricate the emitter and/or back surface field of solar cells. Among the possible techniques, we used radio-frequency plasma enhanced chemical vapor deposition (rf-PECVD) for it is a low thermal budget, scalable, wide-spread process in photovoltaics and it is well-suited to make solar cells on thin c-Si wafers (< 150 μm) without too much stress induced. In this paper, we report the obtaining of n-type epi-Si layers and p-type epi-Si layers by adding a proper amount of phosphine (PH3), diborane (B2H6) or trimethylboron (TMB) to the gas phase as well as appropriately adjusting the deposition temperature, pressure and silane gas flow. For n-type epi-Si layers, we managed to obtain degenerate levels of doping while maintaining the epitaxial growth quality of Si films whereas for p-type we obtained highly doped epi-Si lalers with hole concentration spreading from 2.1018 cm-3 to 6.1019 cm-3 (at 300 K). Another noticeable result is that the deposition temperature dependence of the boron-doped epi-Si films changes according to the doping gas used (TMB or B2H6). This behavior has to be opposed to intrinsic epi-Si for which the higher the temperature the better the epitaxy. We also pay a particular attention to reproducibility of doping levels for n-type and p-type epi-Si layers. Finally, we fabricated c-Si solar cells with p-type epi-Si emitter (entirely epitaxial) and a-Si:H back contact (intrinsic and n-type). In this work we compare our previous results based on laser-cutting and screen-printing for which we achieved an efficiency of 14.2 % [1] with a new fully in-house process in which only SF6 etching is used to define the solar cells and evaporated silver contacts are used for the front grid leading to a solar cell efficiency of 13.4 %.
U2 - 10.1109/PVSC.2010.5614370
DO - 10.1109/PVSC.2010.5614370
M3 - Conference contribution
AN - SCOPUS:78650154840
SN - 9781424458912
T3 - Conference Record of the IEEE Photovoltaic Specialists Conference
SP - 1352
EP - 1357
BT - Program - 35th IEEE Photovoltaic Specialists Conference, PVSC 2010
T2 - 35th IEEE Photovoltaic Specialists Conference, PVSC 2010
Y2 - 20 June 2010 through 25 June 2010
ER -
