PV Manufacturing R&D -- Integrated CIS Thin-Film Manufacturing Infrastructure: Final Technical Report, 2 August 2002--30 April 2004

The objective of this subcontract was to continue the advancement of CIS production at Shell Solar Industries through the development of high-throughput CIS absorber formation reactors, implementation of associated safety infrastructure, an XRF measurement system, a bar code scribing system, and Intelligent Processing functions for the CIS production line. The intent was to open up productionbottlenecks thereby allowing SSI to exercise the overall process at higher production rates and lay the groundwork for evaluation of near-term and long-term manufacturing scale-up. The goal of the absorber formation reactor subcontract work was to investigate conceptual designs for high-throughput, large area (2x5 ft.) CIS reactors and provide design specifications for the first generation ofthese reactors. The importance of reactor design to the CIS formation process was demonstrated when first scaling from a baseline process in reactors for substrates to a large area reactor. SSI demonstrated that lower performance for large substrates was due to differences in absorber layer properties that were due to differences in the materials of construction and the physical design of thelarge reactor. As a result of these studies, a new large area reactor was designed and built that demonstrated circuit plate performance comparable to the performance using small area reactors. For this subcontract work, three tasks were identified to accomplish the absorber formation reactor work: Modeling, Mockup and Vendor Search. The goal of the mockup task was to demonstrate that large areasubstrates, nominally 2 by 5 ft., could be heated without warping and to begin exploring the achievable thermal uniformity for various reactor and substrate configurations and varied ramp rates. The mockup consisted of a metal simulation of the reactor that was placed in a large industrial furnace. Substrate temperature variations ranged from minimal to significant with increasing substrate load. Warping ranged from minimal to significant with increasing substrate load for higher cool down rates. Repeated mockup runs indicated that a slower cool down does not necessarily avoid warping without improvements in thermal uniformity that could not be implemented in the mockup.