Technical progress of high-quality, Ga-doped multicrystalline silicon wafers and solar cells

Average carrier lifetimes above 400 μs are realized after proper P-diffusion and hydrogen passivation on Ga-doped multicrystalline Si wafers cut from a 70 kg ingot where the response to P-diffusion and hydrogen passivation is pronounced. High carrier lifetimes are realized over the whole ingot with minimum values of 20 μs in the top of the ingot indicating the possible use of about 85% of the ingot for solar cell production. The effect of resistivity variation on solar cells conversion efficiency is investigated by means of PC-1D simulation. Conversion efficiencies above 15.5% are realized by utilizing more than 80% of the ingot. Efficiencies as high as 16% are realized on wafers with resistivities higher than 5Ω·cm demonstrating high conversion efficiency in high-resistivity, p-type multicrystalline silicon wafers.