Investigation of intergrain compounds in sputtered Mo films applied in CuIn1−xGaxSe2-based solar cell

Sputtered molybdenum (Mo) thin film is commonly used as back contact in CuIn1−xGaxSe2 (CIGSe)-based solar cell. However, when grown directly on soda-lime glass (SLG) substrate, such Mo layer does not only act as electrical contact but also as tuner for the Na availability during CIGSe growth. Contro...

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Bibliographic Details
Published in:Surface & coatings technology 2012-10, Vol.211, p.29-32
Main Authors: Gautron, E., Tomassini, M., Arzel, L., Barreau, N.
Format: Article
Language:English
Subjects:
Applied sciences
CIGSe
Condensed Matter
Cross-disciplinary physics: materials science
rheology
EELS
Exact sciences and technology
Materials Science
Metals. Metallurgy
Mo oxides
Physics
Production techniques
Sodium
Surface treatment
Surface treatments
TEM
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Summary:Sputtered molybdenum (Mo) thin film is commonly used as back contact in CuIn1−xGaxSe2 (CIGSe)-based solar cell. However, when grown directly on soda-lime glass (SLG) substrate, such Mo layer does not only act as electrical contact but also as tuner for the Na availability during CIGSe growth. Control of the diffusion of sodium from SLG to CIGSe is possible by adjusting the Mo intergrain properties. Samples were prepared by direct current magnetron sputtering with argon pressure of 0.3, 1.2 and 2.0Pa. Transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) have been used to characterize intergrain areas; it is observed that they are amorphous and their width increases from few tenths to several nanometers with the Ar sputtering pressure. Low loss region EELS spectra acquired within these intergrain zones have been compared to reference spectra acquired in the same experimental conditions on well known compounds. The presence of sodium within the intergrain areas, most probably in sodium molybdate form and intercalated in molybdenum trioxide, has been confirmed. ► Sputtered Mo thin film as tuner for the sodium availability during CuIn1−xGaxSe2 growth. ► Increase of amorphous phase content between the Mo columns with argon pressure. ► Comparison of low loss EELS in the intergrain zones of Mo film to reference spectra. ► Sodium within the intergrain areas in sodium molybdate form and intercalated in MoO3.
ISSN:0257-8972
1879-3347
DOI:10.1016/j.surfcoat.2011.09.030