Adjustment of resistivity for phosphorus-doped n-type multicrystalline silicon

In this work we present a novel approach to reduce inhomogeneity of resistivity for n-type phosphorus-doped directionally solidified silicon ingots by using complex arrangements on influencing dopant transport during growth process, which involves adjustments of melt flow and gas transport. In order to obtain more uniform resistivity profile over ingot's height, different process conditions were tested on G1-sized (22 × 22 × 12 cm3) n-type directionally solidified ingots, including altering of ambient gas pressure, enhanced melt mixing with travelling magnetic fields and variations of argon flow above the melt. The quality of ingots was characterised in terms of electrical resistivity and minority carrier lifetime, as well as the presence of impurities and inclusions. The influence of process parameters on material quality will be discussed. It will be shown that a complex approach to melt stirring and gas transport is an effective way to control resistivity distribution along the height of phosphorus-doped multicrystalline ingots, which makes it possible to provide n-type ingots with resistivity profiles comparable to p-type boron-doped ones.