Deconfounding the Effects of Cu and Cr on Perceived Fe Contamination in Si Using an SPV Technique

The effects of iron, copper, and chrome on minority carrier diffusion length measurements in p type, boron doped, silicon were investigated using a surface photovoltage (SPV) technique. Attempts were made to reproduce previous results for iron and chrome, metals which form complexes with boron. Also an attempt was made to study the effect that copper contamination would have upon the SPV results. It was found that the iron results were reproducible, FeB could be photodisassociated, and that the chrome contaminated wafers were not effected by the photodisassociation, CrB pairs were not broken. The copper contaminated wafers were found to be effected by the photodisassociation step, which significantly reduced the measured diffusion lengths