| abstract |
In preparing a solar cell, minute projections and recesses are uniformly formed in a surface of a single crystal silicon substrate or a polycrystal silicon substrate by dipping in an etching liquid composed of a mixed acid which is composed mainly of a hydrofluoride acid, a nitric acid and a phosphoric acid in addition to a surface active agent. A solar cell having a substrate in which spherical projections and recesses are formed in a surface of it to which light is incident; an apparatus for producing efficiently a solar cell by realizing the above-mentioned process, and a wet etching apparatus to effect stably the above-mentioned process to thereby maintaining a concentration of a nitric acid to be constant, are provided. |