Minority carrier lifetime scan map in crystalline silicon wafers

Improved resolution lifetime scan map of minority carriers in excess in mon ocrystalline and multicrystalline silicon wafers are obtained by means of t he phase-shift technique at a practically constant injection level. This te chnique is contactless, based on reflected microwave power variations which occur when the sample is illuminated by a focused near infrared light. Sur faces are passivated by means of an aqueous iodine solution, whose passivat ing efficiency is remarkably constant. Scan maps are obtained with a latera l resolution of 50 mu m thanks to a coaxial cable which directs 9,4 GHz mic rowaves onto the wafer and a fiber coupled laser diode which generates mino rity carriers in excess. Lifetime scan maps are found to be in acceptable a greement with minority carrier diffusion length scan maps obtained by the l ight beam induced current technique. (C) 1999 American Institute of Physics . [S0034-6748(99)04510-4].