Fabrication of an ultra-thin silicon solar cell and nano-scale honeycomb structure by thermal-stress-induced pattern transfer method

A 3 μm thick silicon layers with nano-scale honeycomb structure on the surface were fabricated using the mask-less process, “Thermal-stress Induced Pattern Transfer method”. The thin silicon layer was deposited on a patterned sapphire substrate with nano-scale pyramids, followed by a metal layer printing on the top of the thin silicon layer. After thermal treatment, a thin silicon layer was peeled off from the patterned sapphire substrate and was transferred to the metal layer. Meanwhile, the periodic patterns on the sapphire substrate were transferred to the thin silicon layer forming the honeycomb structure on the surface of the silicon layer. The whole process was operated at a low temperature below 250 °C without any mask process. Finally, the solar cell was fabricated on the silicon thin layer and its performance was measured. The short circuit current density is 0.11 mA/cm2.