Improved performance of thin-film solar cells using surface-morphology-controlled poly-Si films crystallized by flash lamp annealing

We improve the performance of thin-film solar cells using polycrystalline silicon (poly-Si) films formed by flash lamp annealing (FLA) of precursor amorphous Si (a-Si) films on glass substrates by modulating their surface structures. The surface morphology of the poly-Si films can be easily controlled by conventional wet chemical etching using mixed acid of HF and HNO₃, accompanied by effective reduction in optical reflectance. Solar cells with the best performance are obtained when the poly-Si films have the smallest surface roughness. This enhancement of the performance can be understood as the improved coverage of the poly-Si surface with post-deposited doping layers as well as the more effective anti-reflection effect caused by the wet etching.