| Solar-grade polycrystalline silicon was directionally solidified by the Bridgman method using split, reusable graphite molds coated with Si₃N₄ powder. The impurity content, grain size and dislocation etch-pit density(EPD) of the polycrystalline silicon wafers which affect the conversion efficiency of the solar cell were investigated and compared with the reference values reported for high efficiency silicon solar cell. According to the X-ray diffraction analysis, preferred orientation was <111>. The resistivity decreases from 3 to 2Ω·㎝, while the carrier concentration increases from 4.0 to 6.0×10^(15)㎝^(-3) with increasing growth rate and fraction solidified. The presence of B which can be acting as a carrier, is thought to be the main factor causing such a decrease in resistivity. |
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