Lateral Size Effect in the Lifetime Measurement by Frequency-Dependent Surface Photovoltage Technique^*

Effective lifetimes measured with the frequency-dependent surface photovoltage method, decrease in proportion to the quantity of excess carriers escaping from the photocarrier injection point towards the lateral surfaces where they recombine. It has been experimentally found that the separation between the sandpaper-lapped surfaces and the photocarrier injection point has to be longer than 8 times the diffusion length L of minority carriers in order to keep measurement errors under 10%, while it may be more than 1.4L for the chemically etched surfaces.