Investigation of surface features using reactive ion etching method for the enhanced performance of multi-crystalline silicon solar cells

Abstract

Maskless, random RIE texturing with a gas mixture of SF6/O2 (SO) and SF6/O2/Cl2 (SOC) was investigated to achieve higher efficiency for mc-Si solar cells. Cone structure with aspect ratio of 3.7 was highly effective for reducing surface reflectance particularly for wavelength from 310 to 700nm and triangular pyramid structure with aspect ratio of 2 revealed rather uniform reduction of reflectance with respect to the optimized wet texturing for whole wavelength range of 310–1100nm. On the contrary to results of reflectance, performances of fabricated cell were much better for triangular pyramid structure than cone structure. The degradation of cell performances for the cone structure was assigned both to the poor e-h pair generation efficiency relevant to the formation of highly defective surface layer with high density recombination centers, and ohmic shunt. The efficiency enhancement by 0.6% in mc-Si solar cells with triangular pyramid structures was assigned also to the slightly enhanced e-h pair generation efficiency with respect to the reference cell.