Effective surface passivation on multi-crystalline silicon using aluminum/porous silicon nanostructures

Abstract

In this work, we present a novel passivation treatment for multi-crystalline silicon (mc-Si) based on a combination of aluminum/porous silicon nanostructures (Al/PSN). The proposed treatment demonstrates excellent passivation properties, resulting in a significant increase of the effective lifetime of carriers (by up to 98%). In order to investigate and quantify the surface passivation level, the mc-Si samples were characterized by: Scanning electron microscopy (SEM), WCT-120 Sinton silicon wafer lifetime tester system in the QSS mode, Fourier transform infrared spectroscopy (FTIR and two dimensional mapping of the generated current by a laser beam induced current (LBIC). The present work demonstrated that this process not only ensures a high passivation of multi-crystalline silicon substrate but also decreases the surface reflectivity, i.e. from 30% for untreated sample to about 2% for Al/PSN treated ones. Moreover, this amelioration is characterized by a significant reduction of the effective surface recombination (i.e.1.5 cm s−1).It is also clearly demonstrate that the IQE increase from 20% for untreated mc-Si to 60% after Al/PS passivation. These results indicate that mc-Si surface passivation using Al/PSN is a very effective method to ameliorate the quantum efficiency of the mc-Si solar cell.