Options
2004
Conference Paper
Titel
Evaluation of dopant sources and deposition methods suitable for in-line diffusion in the PV industry
Abstract
Several methods of depositing the phosphorus-doped material on silicon wafers prior to in-line emitter diffusion were evaluated, and ultrasonic spraying at room temperature of an aqueous solution of phosphoric acid was selected for the development of a diffusion process. The addition of a small quantity of a commercial surfactant to the solution allowed the sprayed droplets to completely wet the hydrophobic silicon surface, instead of forming a layer of coalesced droplets. Wafers covered with the continuous liquid layer were shortly baked and then heated up to high temperatures in an in-line diffusion furnace. Sheet resistance was varied within the range commonly used for industrial solar cells (37-62 ohm/sq) and was satisfactorily homogeneous across the wafer.