Pulsed-laser-deposited lead sulfide nanoparticles based decoration of porous silicon layer as an effective passivation treatment for multicrystalline silicon

摘要

We report on the use of pulsed laser deposition (PLD) of PbS nanoparticles (PbS-NPs) on porous silicon layers in order to passivate multicrystalline silicon (mc-Si) substrates intended for solar cells applications. The porous silicon (PS) layer was first obtained through the electrochemical anodization of the me-Si substrate, and then the PLD technique was used to decorate the PS layer by PbS-NPs at room temperature. By varying the number of laser ablation pulses (N-LP) from 50 to 1200, the average size of the PbS-NPs was varied from similar to 2 nm to similar to 10 nm. The X-ray diffraction analysis has confirmed the crystalline quality of the PbS-NPs, whereas the transmission electron microscopy observations showed the uniform decoration of the PS by the PbS-NPs. By combining different characterization techniques, we were able to identify N-LP = 200 as the optimal decoration condition that leads to the best passivation, in terms of the lowest surface reflectivity (of 15% at 500 nm wavelength), the highest PL intensity of the PS layer (centered around 633 nm) and the longest minority carrier lifetime (as long as similar to 430 mu s versus 40 mu s for the bare treated PS layer and 2.2 mu s for the untreated bare me-Si).