Passivation of boron emitters on n-type silicon by plasma-enhanced chemical vapor deposited silicon nitride

A well-passivated emitter is crucial to making high efficiency solar cells. With several reported potential benefits in using n-type silicon compared to p-type silicon for solar cell applications, there is a need to investigate silicon nitride passivation on boron-diffused emitters. The passivation of plasma-enhanced chemical vapor deposited silicon nitride with different refractive indices on a variety of boron doping profiles on 1Ωcm, float zoned, n-type silicon is studied. Contrary to the general perceptions that silicon nitride provides relatively poor passivation on boron-diffused surfaces, our results show that for some diffusion sheet resistances and with sufficient annealing, silicon nitride can be particularly well suited for passivating boron emitters. One-sun implied open circuit voltages of 663 and 718mV and dark saturation current densities of 25 and 13fA∕cm2 per side are achieved by silicon nitride passivation on moderately doped boron emitters (100Ω∕sq) and lightly doped boron emitters (240Ω∕sq), respectively.