Evolution of metal impurities during crystalline silicon solar cell processing

Metallic impurities can have a severe negative impact on the electrical properties of multicrystalline silicon. Understanding how metal impurities evolve over the course of solar cell processing is essential to determining their impact on final device performance, and further engineering these defects into their least detrimental configuration. Herein we present a summary of the results of several recent investigations into the evolution of metallic impurities during solar cell processing, including the types and nature of impurities present after ingot crystallization; the effectiveness of phosphorous diffusion at removing and passivating different types and levels of metallic impurities; and the relationship of the hydrogen passivation step to metal impurities, as observed in synchrotron investigations of solar cells material.