A new method of measuring excess carriers lifetime in semiconductors is described. This method is for measuring photoconductive phaseshift of spreading resistance under a point contact. The expressions of various results are derived at various spectral components of exciting light and under various surface conditions. The calculated results for numerical values are given for commonly used conditions of measurement i.e. ground surface and exciting light of long wavelength. At the same time, a more detailed analysis and discussion are presented for these results. This method possesses many advantages, for example, (l) it can be used for measurement on ingot crystal; (2) the surface treatment is very simple; (3) no fixed electrode has to be made on the specimen; (4) measuring apparatus used is simple and easy to operate; (5) enough accuracy is obtainable.This method can be applied to test inhomogeneous specimen. It is used for study in scientific research institutions and it is more suitable for examining single crystal materials in the works. The measurements are made by this method on Ge and Si specimens. Results are in agreement with those obtained by other methods.
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