Low temperature diffusion and its impact on hydrogenation

The impact of a low temperature diffusion (LTD) step at about 650 °C after emitter diffusion on the performance of silicon solar cells is investigated. Neighbouring wafers from a silicon ingot with and without LTD were chosen to make the cells using screen printed techniques. The efficiency was measured and detailed photoluminescence images were performed for the cells with and without LTD. It is found that LTD can significantly increase the efficiency of the cells about 2% by a gettering effect. The post-firing hydrogen passivation was then applied to the screen printed cells made with and without LTD. The efficiency and photoluminescence image before and after post-firing hydrogen passivation were measured to examine the impact of hydrogenation on the cells made with and without LTD. It is found that cells with LTD can respond better to hydrogenation.