PS/Al-µPs Surface Modification for Enhanced Optical and Electronic Performance of Multicrystalline Silicon

In this paper, we report on the effect of combining porous silicon with aluminum microparticles (PS/Al-µPs) on the optical and electronic properties of multicrystalline silicon (mc-Si). An aluminum film was deposited on the mc-Si surface, annealed at 750 °C for 20 min, and partially remained on the surface after CP4 treatment. The surface was subsequently treated with a stain-etching solution (HF/HNO3/H2O) to form a porous silicon (PS) layer. The resulting mc-Si with PS/Al-µPs modification led to a marked improvement in the optoelectronic performance of the treated mc-Si. Surface reflectance was reduced from 34.6% to 9.1% across 400–800 nm wavelength range, corresponding to a 74% decrease. Minority carrier lifetime increased from 2 µs in untreated samples to 1 ms after Al-µPs passivation and remained elevated at 285 µs following stain etching. Additionally, the effective surface recombination velocity dropped from 50 cm·s−1 to 0.35 cm·s−1 and a reduction in [Fe] after treatment confirms the effectiveness of the PS-Al-µPs gettering process. FTIR analysis confirmed the formation of Si–H and Al–O bonds, highlighting effective surface passivation and suppression of recombination losses.