Enhanced Gettering of Multicrystalline Silicon Using Nanowires for Solar Cell Applications

In this work, we present a gettering technique for multicrystalline silicon (mc-Si) by combining a nanowire structure with thermal treatment under nitrogen in an infrared lamp furnace. The silicon nanowires were elaborated using the Silver Nanoparticles Chemical Etching (Ag-NPsCE) technique. The optimal conditions for achieving effective gettering were determined based on the minority carrier lifetime (τeff) measurements. The results show τeff as a function of the gettering temperature and etching time, both before and after the removal of Ag nanoparticles using HNO3. In both cases, the surface was identically treated with a 10% HF dip immediately prior to the carrier lifetime measurements. The highest τeff value, prior to Ag removal, was obtained after an etching duration of 3 min and was 6 µs at an excess carrier density Δn = 1 × 1014 cm−3. Moreover, τeff improves after silver removal. Therefore, removing Ag atoms using an aqueous HNO3 solution is necessary to prevent this issue. Following Ag nanoparticle removal, τeff further increases, reaching 19 µs at a gettering temperature of 850 °C. Similarly, the electrical conductivity (ρ) and carrier mobility (μ) improve significantly after gettering, where the resistivity increases from 5.5 Ω·cm for the reference mc-Si to 1.9 Ω·cm, and the mobility rises from 122 cm2·V−1·s−1 to 253 cm2·V−1·s−1 after nanowire-based gettering at 850 °C. Overall, this method provides a scalable, practical, and cost-effective route to optimize mc-Si for high-performance photovoltaic applications.