Nano-textured topography introduced at room temperature for light-trapping enhancement

In this paper, a unique two-step method is developed to fabricate a nano-textured SnO2 coating. Nano-textured topography is successfully introduced at room temperature by evaporating Sn in a relatively high pressure. Nano-textured SnO2 coating is obtained by annealing in air, with lateral size of nearly 1 μm and root-mean-roughness of over 140 nm. Two structures: substrate and superstrate, are investigated to reveal the light-trapping efficiency. With only 300 nm thick Si absorber layer, the average reflectivity under AM 1.5 illumination spectrum can be limited at 14% and 7%, respectively. This technology is suitable for mass production.