OPTIMUM SENSITIVITY AND 2-DIMENSIONAL MODELING OF MICROWAVE DETECTED PHOTOCONDUCTANCE DECAY CARRIER LIFETIME MEASUREMENT

Optimization of the measurement sensitivity using closed form analytic al expressions derived from an electrical equivalent circuit is carrie d out for microwave detected photoconductance decay system used for no ndestructive carrier lifetime measurement in silicon wafers. The effec t of transverse inhomogeneity in the sample conductivity on the microw ave power reflection is discussed using the equivalent circuit model. The effect of lateral inhomogeneity in the sample conductivity due to local illumination by a source with a laterally varying intensity is s tudied using an elaborate analytical two-dimensional model. Finally, t he effect bf transient lateral carrier diffusion in a sample subjected to a pulsed illumination on the extracted value of the lifetime is in vestigated. (C) 1997 American Institute of Physics.