Hydrogenation of polycrystalline silicon films for passivating contacts solar cells
Thien N Truong, Di Yan, Andres Cuevas, Daniel Macdonald, Hieu T Nguyen
The Australian National University, Canberra, ACT 2601, Australia

We characterize and discuss the impact of hydrogenation on the performance of phosphorus doped polycrystalline silicon (poly-Si) films for passivating contact solar cells. Combining various characterization techniques including transmission electron microscopy, energy dispersive X-ray spectroscopy, low-temperature photoluminescence spectroscopy, quasi steady-state photoconductance, and Fourier-transform infrared spectroscopy, we demonstrate that the hydrogen content inside the doped poly-Si layers can be manipulated to improve the quality of the passivating contact structures. After the hydrogenation process of poly-Si layers fabricated under different conditions, the effective lifetime and the implied open circuit voltage are improved for all investigated samples (up to 4.75 ms and 728 mV on 1 Ω.cm n-type Si substrates). Notably, samples with very low initial passivation qualities show a dramatic improvement from 350 μs to 2.7 ms and from 668 mV to 722 mV.