Four tasks were investigated in this program. Identification of Freon recycling as a low-cost wafer cleaning method was made. An ultrasonic vapor degreaser that utilizes the Freon recycling technique was ordered. Equipment was acquired to produce clean dry air. It was concluded that the low cost clean dry air system can replace the high cost dry nitrogen system without any adverse effects in the solar cell electrical performance. The texturizing process time in large scale production was found to be variable when chemical concentrations and temperatures in the two stage texturizing process were held constant. The introduction of a low temperature intermediate gettering step in combination with a two stage texturizing process sequence was shown to produce a large improvement in solar cell efficiencies. Gettering improved the quality of silicon wafer material. Experimental results also showed that gettering improved the electrical performance of spray-on doped solar cells. Sensor Technology's standard production process utilizing the gettering treatment produced an average batch efficiency of 13.3%. The highest solar cell efficiency obtained from this batch was 14.3%. (ERA citation 05:013271)
展开▼
