Minority carrier lifetime enhancement in multicrystalline silicon by means of a dual treatment based on porous silicon and sputter-deposition of TiO2:Cr passivation layers

We report on a dual passivation approach of multicrystalline-silicon (mc-Si), which combines porous silicon (PS) treatment and sputter-deposition of TiO2:Cr passivation layer. At the optimal Cr content of 2 at.%, the effective minority carrier lifetime was found to be enhanced significantly by more than 2 orders of magnitude (from 2 to ∼733 μs). Our results demonstrate that this dual treatment not only provides strong passivation of the mc-Si substrate but decreases also the total surface reflectivity at 500 nm (from 40% for untreated mc-Si samples to ∼19% for TiO2:Cr/PS treated ones).