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In this work a novel passivation technique is proposed for multicrystalline silicon wafers for the purpose of solar cell application. The new method combines the use of double treatment based on porous Si and TiO2 passivation. Porous silicon (PS) was prepared by electrochemical anodization of multi crystalline substrates (mc‐Si) under different conditions of current density (The current density used is between 3 and 50 mA/cm2). It was demonstrated that the porosity increases with increasing current density from 27, 66% to 81%. TiO2 nanoparticles with different nanometric sizes were incorporated inside pores by the way of the pulsed laser deposition (PLD) technique. The deposited layers have been characterized by spectrophotometry, Fourier transform infrared spectroscopy (FTIR) analysis. It was found that the binary structure of TiO2/PS minimizes the average reflectivity of the mc‐Si substrates from 36% for bare multi crystalline silicon to around 14% for treated substrate. The TiO2/porous Si treated samples present high photoluminescence intensity and an enhancement of the optoelectronic properties. As a result the effective minority carrier lifetime shows a strong improvement after the combined treatment (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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This work reports on passivation effect of solar-grade multicrystalline Si (mc-Si) using a TiO 2 /porous silicon double coating. For this purpose, TiO 2 nanoparticles were deposited onto porous silicon (PS)/mc-Si using pulsed laser ablation of titanium target. The structural and optoelectronic properties of the TiO 2 /PS treated mc-Si substrates were investigated by X-ray diffraction, Raman spectroscopy, optical spectrometry, photo-conductance and photoluminescence (PL). It was found that the minority carrier lifetime (s eff ) of the mc-Si wafer could enhance at a nominal thickness of the TiO 2 film (nanoparticle sizes). This was attributed to a surface passivation of the mc-Si wafer via TiO 2 -passivation of the PS film, whose PL intensity improves consequently. An optimal TiO 2 thickness of 80 nm was found to give the highest PL intensity and an enhancement of the minority carrier lifetime from 5 ls for untreated mc-Si wafer to about 391 ls for a TiO 2 / PS treated wafers.