Ultraviolet Laser Activation of Phosphorus‐Doped Polysilicon Layers for Crystalline Silicon Solar Cells

In crystalline silicon photovoltaics (c‐Si PV), a pulsed laser can be used as a substitute for a high‐temperature furnace dopant diffusion/activation step. In contrast to furnace‐based activation, lasers can be used to achieve highly localized doping with controlled dopant concentrations, useful in advanced architectures such as the interdigitated back contact (IBC) solar cell. In this study, a pulsed ultraviolet (UV) laser is utilized for phosphorus dopant activation within a low‐pressure chemical vapor deposited (LPCVD) polycrystalline silicon (poly‐Si) passivated contact layer. The highest implied open‐circuit voltage iVoc values achieved using this approach reach 726 mV. However, this comes at the expense of high specific contact resistivities ρc, which is attributed to a lower dopant concentration across the poly‐Si(n+)/SiOx/c‐Si interface. Regardless, the optimum iVoc, ρc combination is measured at a laser fluence of 0.78 J cm−2 producing values of 712 mV and 89 mΩ‐cm2, respectively. These values are still compatible with high‐efficiency solar cell designs, underscoring the feasibility and effectiveness of this approach. This study explores ultraviolet laser activation of phosphorus dopants in polysilicon passivated contacts for crystalline silicon solar cells. The optimum laser fluence conditions produce an implied open circuit voltage of 712 mV and a contact resistivity of 89 mΩ‐cm2. Hyperdoping is found to occur at the surface of the polysilicon layer with an active phosphorus concentration of ≈1021 cm−3.