Silicon-rich SiO2/SiO2 multilayers: A promising material for the third generation of solar cell

Si-rich-SiO2(SRSO)/SiO2 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 degrees 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 alpha (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.