Brian H. Mackintosh

Multiple EFG Silicon Ribbon Technology as the Basis for Manufacturing Low-Cost Terrestrial Solar Cells

The development of a technology for production of low-cost silicon sheet substrates for solar cells based on the EFG process has been extended to growth of 10 cm wide material. Simultaneous growth of three 10 cm wide ribbons from a multiple ribbon furnace with continuous melt replenishment has been demonstrated. Run lengths were from six to eight hours, at growth speeds of ∼3 cm/minute. A system for automatic control of the ribbon width has been developed and implemented to permit constant width growth over periods of up to three hours without surveillance by an operator. In single cartridge operation, 10 cm wide ribbon has been grown at speeds up to 4.2 cm/minute. Stress levels and buckling for 200 μm thick ribbon grown at high speeds have been low. Efficiencies for large area (∼50 cm2) solar cells prepared from this 10 cm wide ribbon have been shown to reach ∼10% (AM1 and AR coated).