Solar Cell Birefringence

Solar cell (solar panel) birefringence is caused by stress in the silicon manufacturing process.  This stress has been linked to lowered lifetimes in photovoltaic applications¹ and low manufacturing yields.  Hinds Instruments Exicor^® NIR is capable of plotting these stresses in two dimensions in silicon wafers.

Left: Residual birefringence map of sample A (diameter: 90 mm and thickness: 5.25 mm); Center: Residual birefringence map of a 4” silicon wafer; Right: Residual birefringence map of sample B (diameter 65 mm x 65 mm x 10 mm)

Silicon Ingot Birefringence

Residual stress birefringence in the bulk ingots can be identified using the Exicor NIR system.  Through process evaluation, this measurement can help identify problem material before it is processed, improving sawing yield and minimizing the investment in potentially problematic materials.

Above: Residual birefringence map of a silicon ingot showing low birefringence on the right end.

SYSTEMS AVAILABLE:

Exicor® NIR

FURTHER READING

Stress in Silicon

¹ Shijiang He, Steven Danyluk, I. Tatasov, and Sergei Ostapenko, “Residual Stresses in Polycrystaline Silicon Sheet and Their Relation to Electron-Hole Lifetime”, Appl. Phys. Lett. 86, 251910 (2005)

B. Wang, “A Near Infrared Linear Birefringence Measurement System Using a Photoelastic Modulator”, SPIE Proceedings, Vol. 4399, June 2001

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