Evaluation of microroughness at SiO/sub 2//Si interfaces for high-efficiency crystalline Si solar cells

Microroughness at SiO/sub 2//Si interfaces has been characterized using noncontact spectroscopic ellipsometry. From simulation, the peak height at E/sub 2/ photon energy in imaginary dielectric functions was very sensitive for the microroughness measurement. The ellipsometric method was confirmed by an atomic force microscope. Using HF etching to remove an SiO/sub 2/ overlayer on the Si surface, microroughness tended to decrease with the decrease of HF concentration. Using a diluted 5% HF solution, SiO/sub 2//Si interfaces were denuded and evaluated by spectroscopic ellipsometry. The microroughness seems to affect carrier recombination at the SiO/sub 2//Si interfaces.