Innovative process for the production high-purity zeolites to passivate silicon's surface and bulk to improve electrical parameters

Abstract

Metal impurities in silicon wafers severely degrade solar cell performance, with typical efficiency losses of 15–30 % due to reduced minority carrier lifetimes. While conventional gettering techniques achieve impurity reduction, they require high temperatures (>850 °C) and can introduce wafer damage. This study demonstrates a novel low-temperature (350 °C) gettering approach using Heulandite-Na (HEU-Na) zeolite layers deposited on porous silicon substrates via sol-gel dip-coating. Microwave photoconductance decay (μW-PCD) measurements revealed that the HEU-Na gettering increased minority carrier lifetime from 1.44 μs to 30.68 μs - a 21-fold improvement that surpasses conventional PDG (typically 3-5x enhancement). Surface photovoltage analysis showed diffusion length improvements from 103.27 μm to 324.16 μm, while Hall effect measurements demonstrated a mobility increase from 209.49 to 732.93 cm²V⁻¹s⁻¹. The dual functionality of HEU-Na as both a gettering and passivation layer, combined with its low-temperature processing, offers a cost-effective and industry-scalable approach for improving silicon solar cell efficiency. This method's effectiveness at temperatures below 400 °C makes it particularly valuable for advanced cell architectures where high-temperature processing must be avoided. The findings demonstrate the potential of zeolite-based gettering to revolutionize silicon purification in both photovoltaic and semiconductor industries, potentially reducing manufacturing costs while improving device performance.