A light-trapping structure based on BiO3 nano-islands with highly crystallized sputtered silicon for thin-film solar...

Silicon films with light-trapping structures are fabricated based on Bi2O3 nano-islands, which are obtained by annealing Bi nano-islands in the air at 400 °C. The topography exhibits the maximum altitude of over 600 nm and the root-mean-square roughness of 150 nm, with the lateral size of single island of about 1 μm. Highly crystallized sputtered silicon, realized by Cu-induced crystallization, is used to be a light-absorbing layer. Reflectivity of the samples with different thickness of silicon has been studied to reveal the light-trapping efficiency. The average reflectivity under AM1.5 illumination spectrum is 12% when silicon is 480 nm thick and the reflectivity for the long wavelength region between 800 nm and 1100 nm is less than 10% when the silicon is 1.2 μm thick. This is a promising low-cost structure for crystallized silicon thin-film solar cells with high efficiency.