National Center for Photovoltaics Process Integration Project: Preprint

The research staff of the National Center for Photovoltaics (NCPV) has excelled in increasing solar cell efficiencies and advancing the understanding of photovoltaic-related materials and devices using their existing deposition, processing, and characterization tool base. However, using our existing equipment, it is becoming increasingly difficult to gain new knowledge about important issuesrelated to process sequencing, growth chemistry and kinetics, interface characteristics, and the understanding of how these interfaces affect device performance. This is due in part to the state of our existing tool set, which lacks sufficient in-situ or real-time measurement capabilities, or lacks access to analytical tools where the sample remains in a controlled environment between depositionor processing and measurement. The existing tool set is difficult to upgrade with these capabilities because they are mostly 'standalone,' which means that they operate independently of each other and without a common substrate size or type. As a result, the NCPV has embarked on a project to provide the infrastructure to allow researchers to gain new knowledge that is difficult-if notimpossible-to obtain with existing equipment. This infrastructure consists of providing flexible and robust integration of deposition, processing, and characterization tools via a standardized transfer interface such that samples move between tools in a controlled ambient. Standardization of control and data management software will enhance the utility of the integrated tools. This concept willalso requires the cooperation of experts from various material technologies and characterization disciplines to work directly with each other to obtain answers to key scientific and technological questions. Ultimately, it will be this synergistic effort between NREL staff, universities, and the photovoltaic (PV) industry around an integrated tool base that will add to the knowledge base, helpingmove many PV technologies forward.