Combined characterization of inhomogeneities in DCM multicrystalline silicon wafers [solar cells]

The qualities of multicrystalline silicon solar cell wafers fabricated by a drip-control method are characterized by a combined method including minority carrier lifetime, diffusion length and laser-beam induced photocurrent maps. Low-quality regions exist at peripheral and top regions of the ingots. The relation between the diffusion lengths and lifetimes measured separately can be approximately described by the usual square root equation. Laser-beam induced current maps of fabricated solar cells are relatively uniform for the inhomogeneous quality wafers. This result suggests that the quality may change during solar cell processing presumably due to gettering lifetime killer impurities