Advanced stacked elemental layer process for Cu(InGa)Se{sub 2} thin film photovoltaic devices

Book · Tue Dec 31 04:00:00 EST 1996

OSTI ID:417672

Probst, V; Rimmasch, J; Riedl, W; Stetter, W; Harms, H; Eibl, O ^[1]; Karg, F ^[2]

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1. Siemens AG, Muenchen (Germany)
2. Siemens Solar GmbH, Muenchen (Germany)

Targeting large area and low cost processing of highly efficient thin film solar modules an advanced stacked elemental layer process for Cu(InGa)Se{sub 2} (CIGS) thin films is presented. Key process steps are (i) barrier coating of the soda lime glass substrate combined with the addition of a sodium compound to the elemental Cu/In/Ga/Se-precursor stack and (ii) rapid thermal processing (RTP) to form the CIGS compound. By this strategy exact impurity control is achieved and the advantageous influence of sodium on device performance and on CIGS film formation is demonstrated unambiguously by means of electrical characterization, XRD, SEM, TEM and SIMS. Sodium enriched and sodium free precursor stacks were heated to intermediate states (300 C--500 C) of the RTP-reaction process. The experiment clearly reveals that on the reaction pathway to the chalcopyrite semiconductor increased amounts of copper-selenide are formed, if sodium is added to the precursor films. TEM-electron diffraction unambiguously identifies the CuSe-phase which is localized at the surface of the forming CIGS-film. Application of these experimental findings in the technique of the optimized and controlled sodium incorporation significantly improves process reproducibility, CIGS film homogeneity over larger substrate areas and shifts the average efficiency of cells and modules to a significantly higher level. This is demonstrated by a 12-cell integrated series connected minimodule with an aperture area of 51 cm{sup 2} and a confirmed efficiency of 11.75%.

• OSTI ID: 417672
• Report Number(s): CONF-960401--; ISBN 1-55899-329-0
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
ALUMINIUM
CADMIUM SULFIDES
CHROMIUM
COPPER SELENIDES
CURRENT DENSITY
EFFICIENCY
ELECTRIC CONTACTS
ELECTRIC POTENTIAL
EXPERIMENTAL DATA
FABRICATION
GALLIUM SELENIDES
GLASS
HEAT TREATMENTS
INDIUM SELENIDES
ION MICROPROBE ANALYSIS
MASS SPECTROSCOPY
MICROSTRUCTURE
MOLYBDENUM
PERFORMANCE
SCANNING ELECTRON MICROSCOPY
SEMICONDUCTOR MATERIALS
SODIUM ADDITIONS
SOLAR CELLS
SUBSTRATES
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
ZINC OXIDES