| 摘要 |
PROBLEM TO BE SOLVED: To enhance photoelectric conversion efficiency while reducing the cost by providing a carbon mother material having first and second major surfaces facing each other, and a semiconductor impregnated inward from the first and second major faces by a specified depth or more. SOLUTION: A carbon mother material (carbon composite material) 20 being employed in a substrate for a solar cell has two major surfaces facing each other. The substrate is impregnated inward from both major faces with a semiconductor, e.g. silicon 21, by a depth of 10 μm or more. If impregnation of the silicon 2 is insufficient, the coefficient of thermal expansion of the carbon mother material 20 has a significant effect and a substrate for the solar cell having the coefficient of thermal expansion close to that of the silicon 21 can not be produced. The silicon 21 must be impregnated by 10 μm deep or more, preferably by 50 μm or more. Thin film of the silicon 21 may be left also on the surface of the carbon mother material 20. |
