| 摘要 |
PURPOSE:To improve the efficiency of a solar battery by forming an etching surface having less light reflection on the surface of a polycrystalline silicon substrate having a crystal grain boundary which was heretofore considered to be impossible. CONSTITUTION:A P type polycrystalline silicon substrate 2 is etched with 10% fluoric acid for 30sec on the surface, and the surface is then cleaned. Then, the substrate 2 is put in a glass vessel in which 300g of sodium hydroxide is filled in alcohol such as 3l of isopropyl alcohol and 12l of water, and an etchant having 85 deg.C of boiling point is boiled by a hot plate, and the etchant is elevationally fluctuated by a fluctuating unit to each for 10min. Then, it is washed, neutralized by hydrochloric acid and fluoric acid, dipped in 20% aqueous hydrochloric acid solution for 3min to neutralize the alkali, further washed for 15min, and then dried. As a result, fine irregular portion 3 is formed on the surface to reduce the reflectivity of the visible light to 5% or less, thereby obtaining a preferable reflection preventing surface. |
