Phosphorus Gettering Improve Metallurgical Poly-Silicon Solar Cell Performance Of Industrialization

For metallurgical silicon lower purity, a short time concentrated phosphorus diffusion gettering process was utilized to improve the original metallurgical silicon minority carrier lifetime. Effects of time, temperature and phosphorus source flow gettering the minority carrier lifetime of metallurgical silicon were studied to get optimum conditions. The minority carrier lifetime, sheet resistance and resistivity, electrical properties and quantum efficiency were tested by minority carrier lifetime tester, four-probe tester, the battery detection and classification system and solar spectral performance tester.The experimental result indicates that, after the removal of silicon surface damage, in950℃,300ml/min phosphorus source flow rate and30minutes’ phosphorus flash gettering, the minority carrier lifetime of original metallurgical silicon was improved from1.1us to2μs, with an increase of80.18%. After phosphorus gettering process, the sheet resistance of metallurgical silicon average value was9QΩ□, the resistivity average value was0.18QΩ·cm. Using this technology in production with the same gettering time and temperature, phosphorus source flow rate was reduced by720ml/min.The effect of phosphorus gettering was good. The average value of the open-circuit voltage, short-circuit current, fill factor and efficiency were improved0.16%,1.1%,0.27%and0.97%,respectively. The rate of qualified products of solar cells was improved from42.5%to91%. Applied to a large batch production of the cells, by adjusting the phosphorus source flow rate to be1000ml/min, the rate of qualified products of metallurgical silicon cells was improved to be80%. Through the phosphorus gettering process, light attenuation metallurgical silicon solar cells of decreased from0.18%to0.106%, The corresponding battery components after light attenuation, the average power increased0.481612W. Compared with the solar cells of conventional chemical purification, after the phosphorus gettering process, the utilization of external quantum efficiency of metallurgical silicon cells was improved obviously in the scope of shortwave. The emitter region quality of solar cells was improved significantly.