All-laser-transfer process for silicon solar cells

This work demonstrates a silicon solar cell fabricated at room temperature by all laser transfer process. The starting p-type silicon had dielectric passivation layers on both sides of the wafer. Instead of the full-area junction on the front, selected line-shaped junctions were formed by the laser transfer process. A phosphorous dopant was laser transferred through the dielectric passivation and antireflection layer followed by metallization using electroplating. The rear contacts were formed by laser transferring of aluminum through the back passivation layer. The room temperature process of laser transfer of dopants replaced the traditional high-temperature drive-in diffusion process. Also, the process of laser transfer of metal contacts was carried out at room temperature without the usage of a high temperature furnace. Initial devices fabricated using the room-temperature all-laser-transfer process without any surface texturing showed current densities as high as 34.5 mA/cm². Results of quantum efficiency and current mapping are reported. The effects of laser parameters and the variation of junction geometry on device performance were also investigated. This all-room-temperature process shows the potential of the laser transfer process in simplifying the fabrication of silicon solar cells and in reducing the manufacturing cost.