Ipvf Institute Photovoltaique Dile Of France

Sainte-Foy-lès-Lyon, France

Ipvf Institute Photovoltaique Dile Of France

Sainte-Foy-lès-Lyon, France
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Leal R.,Ecole Polytechnique - Palaiseau | Leal R.,Total S.A. | Leal R.,Ipvf Institute Photovoltaique Dile Of France | Haddad F.,Ecole Polytechnique - Palaiseau | And 4 more authors.
AIP Advances | Year: 2017

Controlling the doping profile in solar cells emitter and front/back surface field is mandatory to reach high efficiencies. In the current state of the art, these doped layers are made by dopant diffusion at around 900°C, which implies potential temperature induced damages in the c-Si absorber and for which a precise control of doping is difficult. An alternative solution based on boron-doped epitaxial silicon layers grown by plasma-enhanced chemical vapor deposition (PECVD) from 200°C using SiF4/H2/Ar/B2H6 chemistry is reported. The structural properties of the doped and undoped epitaxial layers were assessed by spectroscopic ellipsometry (SE), high resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD). The incorporation of boron has been studied via plasma profiling time of flight mass spectrometry (PP-TOFMS) and secondary ion mass spectrometry (SIMS) measurements. The boron-doped epitaxial layers revealed excellent structural and electrical properties even for high carrier concentrations (>1019cm-3). Sheet resistances between 100 and 130 Ω/sq can been obtained depending on the thickness and the doping concentration, which is within the range of targeted values for emitters in c-Si solar cells. Electrochemical capacitance voltage (ECV) revealed a uniform doping profile around 3.1019 cm-3 and by comparing with SIMS measurement a doping efficiency around 50% has been found. © 2017 Author(s).


Chen W.,Ecole Polytechnique - Palaiseau | Chen W.,Ipvf Institute Photovoltaique Dile Of France | Hamon G.,Ecole Polytechnique - Palaiseau | Hamon G.,Total S.A. | And 7 more authors.
Crystal Growth and Design | Year: 2017

We have been able to synthesize directly the tetragonal Si by low temperature plasma-enhanced chemical vapor deposition using hydrogen and silane as the precursor and carrier gas, respectively. With the optimization of growth conditions, a stable tetragonal epitaxial Si can be grown on a crystalline Si substrate at large scale. By combining X-ray diffraction and high resolution transmission electron microscopy measurements, we found that the epitaxial layer has smaller in-plane but larger out-of-plane lattice parameters as compared to the crystalline substrate. The existence of hydrogen platelets in epitaxy is also observed, which affects the diffraction patterns along that direction. We attribute the formation of tetragonal Si to the hydrogenated-cluster-assisted epitaxy. Other possible reasons including host sites of hydrogen atoms and thermal expansion coefficients are also discussed. © 2017 American Chemical Society.

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