High quality multicrystal line silicon grown by multi-stage solidification control method

We have developed a method for growing high quality multicrystalline silicon (mc-Si) ingots for high efficiency solar cells. Grain size of the me-Si wafers was controlled by the multi-stage solidification method. Impurity concentrations in the mc-Si ingots were also reduced by several ways. The efficiency of mc-Si solar cells produced from such me-Si wafers has reached 18.3% with a cell area of 25 cm(2). In this paper we have investigated this high quality mc-Si by means of electron-beam induced current (EBIC), transmission electron microscopy combined with energy-dispersive X-ray analysis (TEM-EDX), and secondary-ion mass-spectroscopy (SIMS). EBIC results revealed that grain boundaries in MUST mc-Si were electrically inactive at room temperature. No metal impurities were detected at these grain boundaries.