Selenization pathways to 2SSS CIGS manufacturing

In spite of the highly successful development of CIGS at the laboratory level, successful commercialization of the technology has not yet been demonstrated. This is largely due to limited understanding and control of the growth mechanisms. We have developed extensive understanding of these mechanisms for all solid state processing of CIGS(This is a 2-step process which we designate as 2SSS) and are currently using this understanding to guide the development of a CIGS pilot line with square foot area capability. In this paper we focus on the selenization mechanisms which are critical to overall performance and manufacturability. While for manufacturing purposes we employ the 2SSS process, we also use co-deposition to assist understanding. For all processes we find an interrelationship between Se and Ga incorporation. This impacts both materials utilization and film performance. With our novel 2SSS process we can exercise better control over the underlying mechanisms and better optimize the materials utilization/performance tradeoff. This also enables the use of deposition pathways that result in better performance and yield at the manufacturing level that might not be utilized because of excessive Se and/or Ga waste.