Abstract

This paper describes a microwave technique for nondestructive measurement of photoconductivity decay in semiconductor wafers. The microwave setup depicted in Fig. 1 is operated at 36 GHz, and to first order the change in microwave conductivity after the optical pulse has a time constant one-half of the excess carrier decay time constant. Three light sources, a xenon flash, an AIGaAs low power laser, and a GaAs high-power laser, have been used for measurements with a variety of silicon and gallium arsenide wafers. Results obtained with the AIGaAs laser are difficult to interpret because of the low carrier generation levels obtained and ace not presented here. Light sources having different wavelengths are important in the depth profiling lifetime in the defect-free zone (DFZ) silicon and isolating trapping phenomena in gallium arsenide.

© 1986 Optical Society of America