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Rationale for the Copper Indium Gallium Diselenide Cluster Tool

This page provides background information on the rationale for developing the Copper Indium Gallium Diselenide (CIGS) cluster tool in the Process Development and Integration Laboratory.

The CIGS thin-film PV industry currently pursues a variety of processes for deposition of the layers the device comprises, especially the CIGS absorber layer. Processes using vacuum evaporation have demonstrated high performance (11%–13%) in commercial modules but suffer from relatively low throughput and low material utilization. In contrast, fabrication methods based on sputtering, atmospheric processes, chemical vapor deposition, and electro-deposition lag behind in performance but have other demonstrated manufacturing advantages.

These industry module efficiencies are considerably less than the 19.9% of the National Renewable Energy Laboratory's highest-efficiency CIGS cell. The use of the CIGS cluster tool can help to address this efficiency gap and some specific problems facing manufacturability, as expressed by industry, including:

  • Fast deposition rates
  • Kinetic limitations of the reaction of the Cu, In, Ga with Se at different temperatures
  • Limits of CIGS absorber thickness versus device performance (i.e., thinner films)
  • Limitations imposed by the deposition technique on film quality (i.e., evaporation versus sputtering, chemical vapor deposition)
  • Process control of composition, thickness, and end-point detection
  • Diagnostics to probe film quality to enhance throughput and yield
  • Integration of processes similar to what is practiced by industry.