Screen-Printed Si Paste for Localized B Doping in a Back Surface Field

In this letter, Si paste formed by p-type Si nanoparticles (NPs) and an organic solvent is used as the source of B. Si NPs with a diameter of ~30 nm are prepared using the pulsed electrical discharge method. The preprocessed Si wafers (after laser opening) are used as the substrate. Si paste with different percentages of Si NPs is screen-printed above the openings. B atoms diffuse into Si wafers through annealing. Uniform doping profiles are observed under a laser scanning microscope. The B doping is successful as evidenced by secondary ion mass spectroscopy.