Implementation of tunneling pasivated contacts into industrially relevant n-Cz Si solar cells

We identify bottlenecks, and propose solutions, to implement a B-diffused front emitter and a backside pc-Si/SiO2 pasivated tunneling contact into high efficiency n-Cz Si cells in an industrially relevant way. We apply an O-precipitate dissolution treatment to make n-Cz wafers immune to bulk lifetime process degradation, enabling robust, passivated B front emitters with J0 <; 20fA/cm2. Adding ultralow recombination n+ pc-Si/SiO2 back contacts enables pre-metallized cells with iVoc=720 mV and J0=8.6 fA/cm2. However, metallization significantly degrades performance of these contacts due to pinholes and possibly, grain boundary diffusion of primary metal and source contaminates such as Cu. An intermediate, doped a-Si:H capping layer is found to significantly block the harmful metal penetration into pc-Si.