Contamination control challenges on SHJ solar cell processing

We have studied the conversion of thin film photovoltaic factory to Silicon Heterojunction (SHJ) technology adapting thin film PECVD reactors for deposition of passivation layers. In the transition from thin film to SHJ cells, it is crucial to study the impact of defectiveness on cell efficiency due to several factors such as transportation and handling of wafers. By performing photoluminescence maps and particle contamination analysis on the surface of wafers and cells different defectiveness sources have been studied. Once the sources of defects have been identified, we elaborated solutions to mitigate effects and we were able to increase the efficiency of SHJ solar cells by an absolute gain of 4.3%.