Extracting surface and bulk recombination parameters for passivated silicon using photoexcited muon spin spectroscopy

Photoexcited muon spin spectroscopy (photo-μSR) enables depth-resolved measurement of charge carrier lifetimes in semiconductors. In this work, we evaluate the sensitivity of photo-μSR to surface recombination by studying silicon wafers with asymmetric surface passivation. One surface has a surface recombination velocity (SRV) of ∼1 cm/s while the other has an SRV in the range ∼1–10 000 cm/s. Charge carriers are generated using 1064 nm laser excitation and the resulting depth-dependent carrier profiles are modeled using a 1D diffusion equation. By comparing depth-resolved photo-μSR carrier lifetime spectra to simulations, we extract bulk carrier lifetime, which we benchmark against values obtained from photoconductance decay (PCD). With knowledge of the bulk carrier lifetime, we then perform further simulations to extract SRV values. The study demonstrates that photo-μSR can resolve differences in surface passivation quality across a broad range (∼10–5000 cm/s) of SRVs. These findings establish photo-μSR as a powerful tool and complementary method to PCD measurements for disentangling surface and bulk recombination in semiconductor materials and devices.