In-situ diffusion of dopants with dendritic cross-linked growth of a crystalline silicon ribbon

摘要

A dentritic web formation process and apparatus for diffusing dopant impurities into a growing dendritic crystal web to produce photovoltaic cells. A solid dopant diffusion source (90) is arranged in a holder mounted in a vertical thermal element (31) either within the melt furnace (10) or outside the furnace adjacent the furnace exit port (12). The solid diffusion source is heated by thermal conduction from the vertical thermal element and source holder using the furnace heat as a source. Auxiliary heater coils are optionally provided around the vertical thermal element to control the temperature of the solid diffusion source. The source and holder can also be mounted outside the furnace adjacent the exit port and heated using a secondary rapid temperature external heater. The growing dendritic crystal web is exposed to the dopant impurities as part of the web growing process, eliminating the need for a separate diffusion gaseous station and processing. IMAGE