Efficiency of silicon solar cells containing chromium

摘要

Efficiency of silicon solar cells containing about 1015 atoms/cm3 of chromium is improved about 26% by thermal annealing of the silicon wafer at a temperature of 200 DEG C. to form chromium precipitates having a diameter of less than 1 Angstrom. Further improvement in efficiency is achieved by scribing laser lines onto the back surface of the wafer at a spacing of at least 0.5 mm and at a depth of less than 13 micrometers to preferentially precipitate chromium near the back surface and away from the junction region of the device. This provides an economical way to improve the deleterious effects of chromium, one of the impurities present in metallurgical grade silicon material.