| This thesis describes the basis for industrial production process of poly crystalline silicon solar cells and focuses on the surrounding problems of poly crystalline silicon during wet etch process. And wet etching process is a very important step to create crystalline silicon solar cell sheets throughout the process. Wet etching primarily influences the shunt resistance Rsh and reverse leakage current Irev2 of the solar cells parameters. The less or over etching, to be cause the shunt resistance Rsh and the reverse current Irev2 become large, thereby influencing the photoelectric conversion efficiency of the cell.The main problems of poly crystalline silicon of wet etching surrounding contain the too large sheet resistance, over and less etching. The too high acid gas density in etching groove and uneven ventilation in the etching process will lead to too large sheet resistance; the inadequate or excessive water protection,the direction of platoon wind and the air being exhausted, the too slow or fast pump speed will result in that surrounding of silicon over or less etching. The solution destiny and rate in etching groove will affect the etching speed v and high temperature will cause the too fast etching speed,however too fast etching speed is not easy to control, influencing over engraved. But if etching speed is too slow, the surrounding PN junction of silicon is less engraved. |
