Enhancing Si-Nanowire Solar Cell Performance through Fabrication and Annealing Optimization

Abstract

The notable optical and electrical features of Si nanowires (SiNWs) outperform conventional bulk silicon, including a large surface area, antireflective properties, and shorter carrier transportation paths for photovoltaics. However, the key challenge lies in the fabrication and doping of SiNWs for p-n junction. The cost-effective metal-assisted chemical etching (MACE) lets the electrolyte etch the rear surface of the substrate. The dot electrode pattern on the front side and the close-periphery electrode on the rear side reduce the photocurrent collection. The spin-on-doping (SOD) leaves phosphorus clusters on the surface during diffusion, which needs dissolution and activation for doping uniformity. The work employs a modified MACE setup to prevent the electrolyte influence on the rear side and increase the photocurrent collection by modifying the front and rear electrode patterns. The increment in the annealing temperature up to 900 ºC dissolves the surface phosphorus clusters and activates the interstitial phosphorus atoms. The optical measurements and Hall mobility confirm the increased active phosphorus atoms. However, the surface oxidation, tip dissolution, and surface defects reduce the power conversion efficiency above the annealing temperature of 900 ºC. Due to increased shunt resistance, the fabrication modification and the annealing temperature optimization improve the power conversion efficiency and FF by 33.7% and 37.6%, respectively.