Laser scanning technique for the detection of resistivity inhomogeneities in silicon using liquid rectifying contacts

The use of a light-spot scanner presents possibilities of rapid and surveillant measurements of carrier lifetime and resistivity variation in semiconductor crystals. In industrial applications the necessity of a rectifying contact presents problems for further processing of the crystal. Previously, this contact was constructed either by making a p-n junction or a Schottky junction of the wafer under investigation. It is shown here that by using an electrolyte in contact with a plain silicon wafer, one obtains equally accurate measurements of the resistivity variation without contaminating the wafer.