Wafer surface preparation for high-efficiency solar cells

Experiments were conducted to investigate the effect of different surface preparation methods on the cell efficiency and other cell parameters, e.g. Voc, Jsc, etc. Results show that wafer surface quality plays a key role in the etching characteristics of Si wafers. Data also show that pre-cleaning and saw damage removal (SDR) steps are required to normalize the surface of different wafers to render them to relatively similar states when introduced to the alkaline texturization bath. The final cleaning process in which an appropriate pyramid rounding step is added can further enhance the cell performance. At the same time, as low as possible metal signature on the wafers must be guaranteed by an advanced HF/HCl clean prior to the plasma enhanced chemical vapor deposition (PECVD) process.