Manufacture of large-area copper indium (gallium) diselenide thin films for photovoltaic applications

Issues relevant to the commercial-scale manufacture of copper indium (gallium) diselenide (CIS/CIGS) thin films were examined. These include CIS/CIGS formation kinetics, the design of multiple-source, large-area thermal evaporation systems, and optical flux measurement.; Selenizations of copper, indium, and Cu-In precursor films by thermal evaporation at 400°C were performed. The unique aspect of the deposition system was the ability to rapidly quench the samples in about 20 seconds. X-ray diffraction, atomic absorption spectroscopy, and gravimetric analyses were used to characterize the films and quantify the phases present at various reaction times. The data were used to develop a kinetic model applicable to selenization by either H2Se or elemental selenium vapor. The CIS and In2Se3 formation kinetics for co-evaporation processes were also studied. CIS and In2Se3 films quenched during deposition showed no significant evidence of intermediate phases.; The design of multiple-source, in-line CIGS deposition systems was quantitatively examined. A pilot-scale system was successfully designed, constructed, and operated. A proposed design for a commercial-scale system is presented. The use of multiple sources allows significant control over the incident species fluxes at the substrate.; Finally, a flux measurement system using atomic absorption spectroscopy (AAS) was modeled and evaluated experimentally. The system operates by projecting an element-specific optical beam above an evaporation source. The beam is attenuated by the elemental vapor, and this attenuation correlates to the effusion rate from the source. The results indicate that reliable implementation of AAS flux measurement appears to be achievable at both the laboratory and commercial scales.