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Deposition and Properties of Polycrystalline Si for Solar Cells

A tin coated graphite substrate was used for growing polycrystalline Si layers by CVD in the SiCl4–H2 system. A mean grain size of poly-Si layers on the tin coated substrate was 50–100 µm, compared with several microns on an uncoated substrate. Moreover the tin intermediate layer seems to play an important role to make a flat surface. The crystalline size could be further enlarged to 100–500 µm by introduction of melting process before normal CVD. A Schottky barrier solar cell using those poly-Si layers showed the open-circuit voltage of 0.25 V, the shortcircuit current density of 12.8 mA/cm2, fill factor of 59% and conversion efficiency of 2.0% under the solar intensity of 92.8 mW/cm2.