Silicon ribbons made by roller quenching methods

Abstract

Polycrystalline silicon ribbons were prepared by Roller Quenching Methods. Ribbons were obtained flexible and of virtually continuous length, 20μ m to 200μ m in thickness, and 1 mm to 50 mm in width. Microscopic observations of etched ribbon surfaces showed that the average grain sizes were 20μ m to 30μ m. Cross-sectional views showed the ribbons to have a columnar grain structure. Unwanted impurities were undetectable by Auger analysis, except very thin oxygenated layer was present on the surface of the ribbons. By means of DC conductivity and Hall measurements of intentionally doped silicon ribbons, it was found that the active carrier concentration of the ribbons was nearly the same as the doped carrier concentration, from 1014/cm3 to 1020/cm3 , the resistivity of the ribbons were about one order of magnitude higher than that of silicon single crystals, and the Hall mobility parallel to the ribbon axis and perpendicular to the ribbon plane was 1 to 150 cm2 · V-1 · sec−1 and 50 to 700 cm2 · V−l · sec−1, respectively. A solar cell using the present ribbon was made by means of a CVD silicon deposition method. Satisfactory diode characteristics and a conversion efficiency of about 5 % were obtained.