Canada-based Aurora Solar Technologies (AST) has introduced the Decima Gemini solutions, an enhanced version of its Decima inline measurement system, for quality control of bi-facial solar cells during production. Bi-facial solar cells have an open and active backside, which enables collection of reflected light from the earth, rooftops, etc., generating up to 25 per cent more energy than traditional cells. However, bi-facial PV manufacturers have to rely on manual sheet resistance sampling techniques that are inadequate for handling the complex and sensitive bi-facial cell fabrication process.
AST’s Decima Gemini solution has been designed to address this issue. The solution consists of a specialised pair of measurement heads that enables accurate and simultaneous measurement of the sheet resistance of the wafers’ back-surface field and emitter. Each Decima Gemini system is managed and controlled by AST’s Veritas process visualisation software. This unique measurement capability is achieved through Aurora’s patented Infrared Reflectometry measurement technology, which measures doped semiconductor layers without contacting the cell or requiring an electrical junction between the doped layers. Decima can accurately measure the bi-facial cell’s back-surface field without interference from wafer resistivity variations – a crucial need for this type of application.
The Decima Gemini solution is designed as a unit to fit the upper and lower portions of a wafer conveyor. It measures the entire range of wafers at full production line speeds. The Veritas process visualisation software provides process engineers and operators with a simple and single point to monitor and control the critical back-surface field and emitter formation processes.