Silicon-rich SiO_2/SiO_2 multilayers: A promising material for the third generation of solar cell

Abstract

Si-rich-SiO_2(SRSO)/SiO_2 multilayers (MLs) have been grown by reactive magnetron sputtering. The presence of silicon nanoclusters (Si-ncls) within the SRSO sublayer and annealing temperature influence optical absorption as well as photoluminescence. The optimized annealing temperature has been found to be 1100°C, which allows the recovery of defects and thus enhances photoluminescence. Four MLs with Si-ncl size ranging from 1.5 to 8 nm have been annealed using the optimized conditions and then studied by transmission measurements. Optical absorption has been modeled so that a size effect in the linear absorption coefficient α (in cm^(-1)) has been evidenced and correlated with TEM observations. It is demonstrated that amorphous Si-ncl absorption is fourfold higher than that of crystalline Si ncls.